Update CI config for 2024

[takluyver]

• Update Github action versions
• Remove Python 3.6 from Github actions
• Add newer Pythons up to 3.12
• Add the config file which is now required for readthedocs

[codecov[bot]]

Codecov Report

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

Project coverage is 87.71%. Comparing base (1f772ed) to head (1eeacf4).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #265 +/- ## ========================================== - Coverage 88.34% 87.71% -0.63% ========================================== Files 8 8 Lines 798 798 ========================================== - Hits 705 700 -5 - Misses 93 98 +5 ```

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