diff --git a/poetry.lock b/poetry.lock
index 39395ef..04a2605 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -34,7 +34,7 @@ optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 
 [package.extras]
-dev = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface", "furo", "sphinx", "pre-commit"]
+dev = ["coverage[toml] (>=5.0.2)", "furo", "hypothesis", "pre-commit", "pympler", "pytest (>=4.3.0)", "six", "sphinx", "zope.interface"]
 docs = ["furo", "sphinx", "zope.interface"]
 tests = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six", "zope.interface"]
 tests_no_zope = ["coverage[toml] (>=5.0.2)", "hypothesis", "pympler", "pytest (>=4.3.0)", "six"]
@@ -101,6 +101,9 @@ category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, <4"
 
+[package.dependencies]
+toml = {version = "*", optional = true, markers = "extra == \"toml\""}
+
 [package.extras]
 toml = ["toml"]
 
@@ -132,6 +135,7 @@ python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 mccabe = ">=0.6.0,<0.7.0"
 pycodestyle = ">=2.4.0,<2.5.0"
 pyflakes = ">=2.0.0,<2.1.0"
+setuptools = ">=30"
 
 [[package]]
 name = "furl"
@@ -181,7 +185,7 @@ python-versions = ">=2.7,!=3.0,!=3.1,!=3.2,!=3.3"
 zipp = ">=0.5"
 
 [package.extras]
-docs = ["sphinx", "docutils (==0.12)", "rst.linker"]
+docs = ["docutils (==0.12)", "rst.linker", "sphinx"]
 
 [[package]]
 name = "importlib-resources"
@@ -367,18 +371,18 @@ testing = ["argcomplete", "hypothesis (>=3.56)", "mock", "nose", "requests", "xm
 
 [[package]]
 name = "pytest-cov"
-version = "2.11.1"
+version = "4.0.0"
 description = "Pytest plugin for measuring coverage."
 category = "dev"
 optional = false
-python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
+python-versions = ">=3.6"
 
 [package.dependencies]
-coverage = ">=5.2.1"
+coverage = {version = ">=5.2.1", extras = ["toml"]}
 pytest = ">=4.6"
 
 [package.extras]
-testing = ["fields", "hunter", "process-tests (==2.0.2)", "six", "pytest-xdist", "virtualenv"]
+testing = ["fields", "hunter", "process-tests", "pytest-xdist", "six", "virtualenv"]
 
 [[package]]
 name = "pytest-flake8"
@@ -401,8 +405,8 @@ optional = false
 python-versions = ">=3.6"
 
 [package.extras]
-docs = ["sphinx", "jaraco.packaging (>=8.2)", "rst.linker (>=1.9)"]
-testing = ["pytest (>=3.5,!=3.7.3)", "pytest-checkdocs (>=1.2.3)", "pytest-flake8", "pytest-cov", "pytest-enabler", "pytest-virtualenv", "pytest-black (>=0.3.7)", "pytest-mypy"]
+docs = ["jaraco.packaging (>=8.2)", "rst.linker (>=1.9)", "sphinx"]
+testing = ["pytest (>=3.5,!=3.7.3)", "pytest-black (>=0.3.7)", "pytest-checkdocs (>=1.2.3)", "pytest-cov", "pytest-enabler", "pytest-flake8", "pytest-mypy", "pytest-virtualenv"]
 
 [[package]]
 name = "python-dateutil"
@@ -428,7 +432,7 @@ name = "pyyaml"
 version = "5.3.1"
 description = "YAML parser and emitter for Python"
 category = "dev"
-optional = false
+optional = true
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*"
 
 [[package]]
@@ -457,7 +461,7 @@ idna = ">=2.5,<3"
 urllib3 = ">=1.21.1,<1.27"
 
 [package.extras]
-security = ["pyOpenSSL (>=0.14)", "cryptography (>=1.3.4)"]
+security = ["cryptography (>=1.3.4)", "pyOpenSSL (>=0.14)"]
 socks = ["PySocks (>=1.5.6,!=1.5.7)", "win-inet-pton"]
 
 [[package]]
@@ -484,7 +488,19 @@ requests = ">=2.0"
 six = "*"
 
 [package.extras]
-tests = ["coverage (>=3.7.1,<5.0.0)", "pytest-cov", "pytest-localserver", "flake8", "pytest (>=4.6,<5.0)", "pytest"]
+tests = ["coverage (>=3.7.1,<5.0.0)", "flake8", "pytest", "pytest (>=4.6,<5.0)", "pytest-cov", "pytest-localserver"]
+
+[[package]]
+name = "setuptools"
+version = "59.6.0"
+description = "Easily download, build, install, upgrade, and uninstall Python packages"
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+
+[package.extras]
+docs = ["furo", "jaraco.packaging (>=8.2)", "jaraco.tidelift (>=1.4)", "pygments-github-lexers (==0.0.5)", "rst.linker (>=1.9)", "sphinx", "sphinx-inline-tabs", "sphinxcontrib-towncrier"]
+testing = ["flake8-2020", "jaraco.envs (>=2.2)", "jaraco.path (>=3.2.0)", "mock", "paver", "pip (>=19.1)", "pytest (>=6)", "pytest-black (>=0.3.7)", "pytest-checkdocs (>=2.4)", "pytest-cov", "pytest-enabler (>=1.0.1)", "pytest-flake8", "pytest-mypy", "pytest-virtualenv (>=1.2.7)", "pytest-xdist", "sphinx", "virtualenv (>=13.0.0)", "wheel"]
 
 [[package]]
 name = "six"
@@ -520,6 +536,7 @@ Jinja2 = ">=2.3"
 packaging = "*"
 Pygments = ">=2.0"
 requests = ">=2.5.0"
+setuptools = "*"
 snowballstemmer = ">=1.1"
 sphinxcontrib-applehelp = "*"
 sphinxcontrib-devhelp = "*"
@@ -530,8 +547,8 @@ sphinxcontrib-serializinghtml = "*"
 
 [package.extras]
 docs = ["sphinxcontrib-websupport"]
-lint = ["flake8 (>=3.5.0)", "flake8-import-order", "mypy (>=0.780)", "docutils-stubs"]
-test = ["pytest", "pytest-cov", "html5lib", "typed-ast", "cython"]
+lint = ["docutils-stubs", "flake8 (>=3.5.0)", "flake8-import-order", "mypy (>=0.780)"]
+test = ["cython", "html5lib", "pytest", "pytest-cov", "typed-ast"]
 
 [[package]]
 name = "sphinx-rtd-theme"
@@ -545,7 +562,7 @@ python-versions = "*"
 sphinx = "*"
 
 [package.extras]
-dev = ["transifex-client", "sphinxcontrib-httpdomain", "bump2version"]
+dev = ["bump2version", "sphinxcontrib-httpdomain", "transifex-client"]
 
 [[package]]
 name = "sphinxcontrib-applehelp"
@@ -556,7 +573,7 @@ optional = true
 python-versions = "*"
 
 [package.extras]
-test = ["pytest", "flake8", "mypy"]
+test = ["flake8", "mypy", "pytest"]
 
 [[package]]
 name = "sphinxcontrib-devhelp"
@@ -567,7 +584,7 @@ optional = true
 python-versions = "*"
 
 [package.extras]
-test = ["pytest", "flake8", "mypy"]
+test = ["flake8", "mypy", "pytest"]
 
 [[package]]
 name = "sphinxcontrib-htmlhelp"
@@ -578,7 +595,7 @@ optional = true
 python-versions = "*"
 
 [package.extras]
-test = ["pytest", "flake8", "mypy", "html5lib"]
+test = ["flake8", "html5lib", "mypy", "pytest"]
 
 [[package]]
 name = "sphinxcontrib-jsmath"
@@ -589,7 +606,7 @@ optional = true
 python-versions = ">=3.5"
 
 [package.extras]
-test = ["pytest", "flake8", "mypy"]
+test = ["flake8", "mypy", "pytest"]
 
 [[package]]
 name = "sphinxcontrib-qthelp"
@@ -600,7 +617,7 @@ optional = true
 python-versions = "*"
 
 [package.extras]
-test = ["pytest", "flake8", "mypy"]
+test = ["flake8", "mypy", "pytest"]
 
 [[package]]
 name = "sphinxcontrib-serializinghtml"
@@ -611,7 +628,7 @@ optional = true
 python-versions = "*"
 
 [package.extras]
-test = ["pytest", "flake8", "mypy"]
+test = ["flake8", "mypy", "pytest"]
 
 [[package]]
 name = "toml"
@@ -667,7 +684,7 @@ optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, <4"
 
 [package.extras]
-secure = ["pyOpenSSL (>=0.14)", "cryptography (>=1.3.4)", "idna (>=2.0.0)", "certifi", "ipaddress"]
+secure = ["certifi", "cryptography (>=1.3.4)", "idna (>=2.0.0)", "ipaddress", "pyOpenSSL (>=0.14)"]
 socks = ["PySocks (>=1.5.6,!=1.5.7,<2.0)"]
 
 [[package]]
@@ -678,9 +695,12 @@ category = "dev"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 
+[package.dependencies]
+setuptools = ">=18.0.0"
+
 [package.extras]
-docs = ["sphinx (>=1.8.0,<2)", "towncrier (>=18.5.0)", "sphinx-rtd-theme (>=0.4.2,<1)"]
-testing = ["pytest (>=4.0.0,<5)", "coverage (>=4.5.0,<5)", "six (>=1.10.0,<2)", "pytest-timeout (>=1.3.0,<2)", "pytest-xdist", "mock", "xonsh"]
+docs = ["sphinx (>=1.8.0,<2)", "sphinx-rtd-theme (>=0.4.2,<1)", "towncrier (>=18.5.0)"]
+testing = ["coverage (>=4.5.0,<5)", "mock", "pytest (>=4.0.0,<5)", "pytest-timeout (>=1.3.0,<2)", "pytest-xdist", "six (>=1.10.0,<2)", "xonsh"]
 
 [[package]]
 name = "zipp"
@@ -691,8 +711,8 @@ optional = false
 python-versions = ">=2.7"
 
 [package.extras]
-docs = ["sphinx", "jaraco.packaging (>=3.2)", "rst.linker (>=1.9)"]
-testing = ["pathlib2", "contextlib2", "unittest2"]
+docs = ["jaraco.packaging (>=3.2)", "rst.linker (>=1.9)", "sphinx"]
+testing = ["contextlib2", "pathlib2", "unittest2"]
 
 [extras]
 doc = []
@@ -703,7 +723,7 @@ travis-ci = []
 [metadata]
 lock-version = "1.1"
 python-versions = "^3.6"
-content-hash = "a18078e1b4a0363f1c0171e88d27f24b80e5a9e8d460836525b282702be6458f"
+content-hash = "095c10770f16f6d95bcc8719ece96f58fff3deacc60ae8ca7c4bb8a6e2fc268b"
 
 [metadata.files]
 alabaster = [
@@ -907,7 +927,6 @@ py = [
 ]
 pycodestyle = [
     {file = "pycodestyle-2.4.0-py2.py3-none-any.whl", hash = "sha256:cbc619d09254895b0d12c2c691e237b2e91e9b2ecf5e84c26b35400f93dcfb83"},
-    {file = "pycodestyle-2.4.0-py3.6.egg", hash = "sha256:74abc4e221d393ea5ce1f129ea6903209940c1ecd29e002e8c6933c2b21026e0"},
     {file = "pycodestyle-2.4.0.tar.gz", hash = "sha256:cbfca99bd594a10f674d0cd97a3d802a1fdef635d4361e1a2658de47ed261e3a"},
 ]
 pyflakes = [
@@ -927,8 +946,8 @@ pytest = [
     {file = "pytest-6.2.3.tar.gz", hash = "sha256:671238a46e4df0f3498d1c3270e5deb9b32d25134c99b7d75370a68cfbe9b634"},
 ]
 pytest-cov = [
-    {file = "pytest-cov-2.11.1.tar.gz", hash = "sha256:359952d9d39b9f822d9d29324483e7ba04a3a17dd7d05aa6beb7ea01e359e5f7"},
-    {file = "pytest_cov-2.11.1-py2.py3-none-any.whl", hash = "sha256:bdb9fdb0b85a7cc825269a4c56b48ccaa5c7e365054b6038772c32ddcdc969da"},
+    {file = "pytest-cov-4.0.0.tar.gz", hash = "sha256:996b79efde6433cdbd0088872dbc5fb3ed7fe1578b68cdbba634f14bb8dd0470"},
+    {file = "pytest_cov-4.0.0-py3-none-any.whl", hash = "sha256:2feb1b751d66a8bd934e5edfa2e961d11309dc37b73b0eabe73b5945fee20f6b"},
 ]
 pytest-flake8 = [
     {file = "pytest-flake8-1.0.7.tar.gz", hash = "sha256:f0259761a903563f33d6f099914afef339c085085e643bee8343eb323b32dd6b"},
@@ -977,6 +996,10 @@ responses = [
     {file = "responses-0.10.15-py2.py3-none-any.whl", hash = "sha256:af94d28cdfb48ded0ad82a5216616631543650f440334a693479b8991a6594a2"},
     {file = "responses-0.10.15.tar.gz", hash = "sha256:7bb697a5fedeb41d81e8b87f152d453d5cab42dcd1691b6a7d6097e94d33f373"},
 ]
+setuptools = [
+    {file = "setuptools-59.6.0-py3-none-any.whl", hash = "sha256:4ce92f1e1f8f01233ee9952c04f6b81d1e02939d6e1b488428154974a4d0783e"},
+    {file = "setuptools-59.6.0.tar.gz", hash = "sha256:22c7348c6d2976a52632c67f7ab0cdf40147db7789f9aed18734643fe9cf3373"},
+]
 six = [
     {file = "six-1.14.0-py2.py3-none-any.whl", hash = "sha256:8f3cd2e254d8f793e7f3d6d9df77b92252b52637291d0f0da013c76ea2724b6c"},
     {file = "six-1.14.0.tar.gz", hash = "sha256:236bdbdce46e6e6a3d61a337c0f8b763ca1e8717c03b369e87a7ec7ce1319c0a"},
@@ -1018,7 +1041,6 @@ sphinxcontrib-serializinghtml = [
     {file = "sphinxcontrib_serializinghtml-1.1.1-py2.py3-none-any.whl", hash = "sha256:01d9b2617d7e8ddf7a00cae091f08f9fa4db587cc160b493141ee56710810932"},
 ]
 toml = [
-    {file = "toml-0.10.0-py2.7.egg", hash = "sha256:f1db651f9657708513243e61e6cc67d101a39bad662eaa9b5546f789338e07a3"},
     {file = "toml-0.10.0-py2.py3-none-any.whl", hash = "sha256:235682dd292d5899d361a811df37e04a8828a5b1da3115886b73cf81ebc9100e"},
     {file = "toml-0.10.0.tar.gz", hash = "sha256:229f81c57791a41d65e399fc06bf0848bab550a9dfd5ed66df18ce5f05e73d5c"},
 ]
diff --git a/pyproject.toml b/pyproject.toml
index 7a5815f..ab6b88b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -34,7 +34,7 @@ arrow = ">=0.12.1,<0.17.0"
 
 [tool.poetry.dev-dependencies]
 pytest = "^6.2"
-pytest-cov = "^2.11"
+pytest-cov = "^4.0"
 pytest-flake8 = "^1.0"
 responses = "^0.10.15"
 pytest-runner = "^5.3"