Update pluggy to 0.13.0

[pyup-bot]

This PR updates pluggy from 0.7.1 to 0.13.0.

Changelog

0.13.0

==========================

Trivial/Internal Changes
------------------------

- `222 <https://github.com/pytest-dev/pluggy/issues/222>`_: Replace ``importlib_metadata`` backport with ``importlib.metadata`` from the
standard library on Python 3.8+.

0.12.0

==========================

Features
--------

- `215 <https://github.com/pytest-dev/pluggy/issues/215>`_: Switch from ``pkg_resources`` to ``importlib-metadata`` for entrypoint detection for improved performance and import time.  This time with ``.egg`` support.

0.11.0

==========================

Bug Fixes
---------

- `205 <https://github.com/pytest-dev/pluggy/issues/205>`_: Revert changes made in 0.10.0 release breaking ``.egg`` installs.

0.10.0

==========================

Features
--------

- `199 <https://github.com/pytest-dev/pluggy/issues/199>`_: Switch from ``pkg_resources`` to ``importlib-metadata`` for entrypoint detection for improved performance and import time.

0.9.0

=========================

Features
--------

- `189 <https://github.com/pytest-dev/pluggy/issues/189>`_: ``PluginManager.load_setuptools_entrypoints`` now accepts a ``name`` parameter that when given will
load only entry points with that name.

``PluginManager.load_setuptools_entrypoints`` also now returns the number of plugins loaded by the
call, as opposed to the number of all plugins loaded by all calls to this method.



Bug Fixes
---------

- `187 <https://github.com/pytest-dev/pluggy/issues/187>`_: Fix internal ``varnames`` function for PyPy3.

0.8.1

=========================

Trivial/Internal Changes
------------------------

- `166 <https://github.com/pytest-dev/pluggy/issues/166>`_: Add ``stacklevel=2`` to implprefix warning so that the reported location of warning is the caller of PluginManager.

0.8.0

=========================

Features
--------

- `177 <https://github.com/pytest-dev/pluggy/issues/177>`_: Add ``get_hookimpls()`` method to hook callers.



Trivial/Internal Changes
------------------------

- `165 <https://github.com/pytest-dev/pluggy/issues/165>`_: Add changelog in long package description and documentation.


- `172 <https://github.com/pytest-dev/pluggy/issues/172>`_: Add a test exemplifying the opt-in nature of spec defined args.


- `57 <https://github.com/pytest-dev/pluggy/issues/57>`_: Encapsulate hook specifications in a type for easier introspection.

Links

• PyPI: https://pypi.org/project/pluggy
• Changelog: https://pyup.io/changelogs/pluggy/
• Repo: https://github.com/pytest-dev/pluggy