Improvements and housekeeping for 2024-W15

[khaeru]

• Use Pint's documented approach to cache registry instantiation.
• Actually test against the earliest supported Pint version shown in pyproject.toml.
• Add Python 3.12 to classifiers.
• Replace black with ruff for code formatting.
• Use latest ruff, mypy.
• Bump GitHub Actions used in workflows, and add dependabot config to update these automatically in the future.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 78.61%. Comparing base (e22eab6) to head (d8e2abd).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #48 +/- ## ========================================== + Coverage 75.28% 78.61% +3.32% ========================================== Files 5 5 Lines 174 173 -1 ========================================== + Hits 131 136 +5 + Misses 43 37 -6 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[khaeru]

Actually test against the earliest supported Pint version shown in pyproject.toml.

Here we see:

AttributeError: module 'numpy' has no attribute 'alen'

This was removed in numpy 1.23.0, released 2022-06-23. Numpy 1.22.4 only provides wheels up to Python 3.10.