Add test runner for Python 3.12

[OpenBagTwo]

Summary

Resolves #36

List of Changes

• Adds Python 3.12 to the test matrix
• Switches the linter job to run using Python 3.12
• Updates the Python version badges to show compatibility with 3.12

Tech Debt and Other Concerns

Validation Performed

PR Type

• [ ] This PR introduces a breaking change (will require a bump in the minor version)
• [ ] The changes in this PR are high urgency and necessitate a hotfix or patch release (will require rebasing off of release)
• [ ] This is a release (staging) PR (maintainer use only)

Checklist:

• [x] I have read the contributor's guide
• [x] I have run mkdocs serve locally and ensured that all API docs and changes I have made to the static pages are rendering correctly, with all links working
• [x] All tech debt concerns have been resolved, documented as issues, or otherwise accepted
• [x] I agree to license my contribution to this project under the GNU Public License v3

[OpenBagTwo]

Yeah, I opened this when I did because I had a feeling there would be issues with 3.12 for CI/CD this close to roll-out.

I'll plan to rerun the jobs every few days until the issue is resolved.