Drop support for Python 3.9

[andersy005]

Description of proposed changes

• Now that xarray has officially dropped supprt for Python 3.9: https://github.com/pydata/xarray/pull/8937, this PR bumps the required/minimum Python version to 3.10
• Closes #230

[andersy005]

pre-commit.ci autofix

[codecov[bot]]

Codecov Report

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

Project coverage is 97.58%. Comparing base (43c9135) to head (79c5db8). Report is 25 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #232 +/- ## ========================================== + Coverage 96.25% 97.58% +1.32% ========================================== Files 6 6 Lines 347 372 +25 Branches 82 87 +5 ========================================== + Hits 334 363 +29 + Misses 8 6 -2 + Partials 5 3 -2 ```

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