Automate tests with Continuous Integration via GitHub Actions

[RileyWClarke]

• Add new directory named workflows to .github folder #14
• Add YAML file named main.yml to workflows that installs Python dependencies via requirements.txt and runs pytest on tests/test_models.py #15
• Add build matrix to main.yml that automates tests for Python versions 3.10 & 3.11 on MacOS, Windows, and Ubuntu #16

https://shrra.github.io/python-intermediate-development/23-continuous-integration-automated-testing/index.html

[Noi-Shitrit]

It is connected to #5 #5