Fixes #30 Adds automated test coverage GitHub Workflow

[schuylermartin45]

Fixes #30

• Adds 2 small smoke tests that ensure the CLI exits as expected if:
  • The help menu is requested
  • An invalid command is provided
• Adds pytest and pytest-cov as dependencies.
  • I've elected not to include pytest-xdist at this time as with so few tests, the overhead of setting up the workers outweighs any benefits of parallelizing the tests.
  • I decided not to suppress any of the pytest deprecation warnings, in case they are useful.
• Sets the minimum passing test coverage to 35%. With these 2 tests this project is at ~38% coverage.
• Adds a checks.yml file to trigger a GitHub workflow to run the test coverage report for every PR and on merges to main.
• Adds a small section to the README to explain how to run the test coverage

Here's a test run on my fork

[schuylermartin45]

I just noticed that the UI is calling this release-build. Let me fix that real quick