Bump CI jobs to 3.12

[jacobtylerwalls]

No description provided.

[Pierre-Sassoulas]

I'm not sure we have to make the default python interpreter 3.12 yet, but we should test our code on the actual 3.12 not 3.12 dev

[mbyrnepr2]

Error: The version '3.12' with architecture 'x64' was not found for Ubuntu 22.04.
17
The list of all available versions can be found here: https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json

And another, the ReadTheDocs message:
Problem in your project's configuration. Invalid configuration option "build.tools.python": expected one of (2.7, 3.6, 3.7, 3.8, 3.9, 3.10, 3.11, 3, miniconda3-4.7, mambaforge-4.10, mambaforge-22.9), got 3.12

[Pierre-Sassoulas]

Forgot to leave the review when I was on mobile.

[jacobtylerwalls]

(Primer will remain failing until we get a 3.12 run on main.)

[codecov]

Codecov Report

Merging #9092 (6267f03) into main (3cba15b) will increase coverage by 0.00%.
Report is 13 commits behind head on main.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9092   +/-   ##
=======================================
  Coverage   95.75%   95.76%           
=======================================
  Files         173      173           
  Lines       18663    18665    +2     
=======================================
+ Hits        17871    17874    +3     
+ Misses        792      791    -1     

see 2 files with indirect coverage changes

[mbyrnepr2]

3.12 action is available now right? https://github.com/actions/python-versions

[mbyrnepr2]

Do we want to add 3.12 to the tox.ini while we're here?