ci: modernize Python test matrix and GitHub Actions

[6democratickim9]

Issue #404

Changes Proposed

• Test and lint the project on Python 3.10, 3.11, and 3.12.
• Update GitHub Actions and pin them to full commit SHAs.
• Enable pip caching and run both workflows for pull requests targeting dev.

Explanation of Changes

Python 3.9 was removed because the current dependencies require Python 3.10 or newer.

Actions are pinned to full SHAs for reproducibility and security.

fail-fast: false ensures every Python version is tested even if one fails.

Screenshots of new feature/change

[KingAkeem]

The workflow updates look good, and all six matrix jobs are passing. There is one user-facing version mismatch to fix before this is ready to merge.

[KingAkeem]

Thanks for updating the README. The minimum Python version is now consistent across the package metadata and setup docs, and the Python 3.10 through 3.12 test and lint matrix is green. Looks good to merge.