[ORCA-294] Fix tox implementation in CI pipeline

[BWMac]

Problem:

Our CI pipeline is failing to test our code with the intended Python versions.

Solution:

Update ci.yml to use the tox-gh GH Actions plugin.

Notes:

• Once we were testing the Python versions we intended, it became clear that this codebase was not actually compatible with Python 3.8. I am changing the compatibility to 3.9-3.11 as a result. I do not expect this to impact any users.
• tox is no longer a required dependency of the repository because we are installing tox-gh during our CI runs according to the recommended usage.
• This PR will serve as a model for any other repositories we own that use tox in their CI pipeline.
• A GH Action run with these changes can be viewed here.
  • Please verify that the versions listed in the logs for the Run tests steps under tox:py match those expected before approving as a sanity check.

[swarmia]

✅  Linked to Bug ORCA-294 · Update our repositories that use tox to work with newer macos GitHub Actions Runners

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

❗ No coverage uploaded for pull request base (bwmac/ORCA-288/test_object_refactor@ebae79f). Click here to learn what that means.

Additional details and impacted files

@@                           Coverage Diff                           @@
##             bwmac/ORCA-288/test_object_refactor       #53   +/-   ##
=======================================================================
  Coverage                                       ?   100.00%           
=======================================================================
  Files                                          ?        24           
  Lines                                          ?      1184           
  Branches                                       ?       192           
=======================================================================
  Hits                                           ?      1184           
  Misses                                         ?         0           
  Partials                                       ?         0           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[thomasyu888]

🔥 LGTM!