Add Python 3.12 to the CI and tox.

[mbyrnepr2]

PR Checklist

• A description of the changes is added to the description of this PR.
• If there is a related issue, make sure it is linked to this PR.
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated

Description of changes

• Add Python 3.12 which is now available as a github action: https://github.com/actions/python-versions/releases
• Add Python 3.12 tox environment.

[codecov]

Codecov Report

Merging #490 (404ad06) into main (717be42) will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##            main    #490   +/-   ##
=====================================
  Coverage   90.4%   90.4%           
=====================================
  Files         39      39           
  Lines       1084    1084           
  Branches     220     220           
=====================================
  Hits         980     980           
  Misses        89      89           
  Partials      15      15           

[fpgmaas]

@mbyrnepr2 Thanks for the contribution! It seems the deletion of the 3.12-dev CI checks is not picked up properly. Can you try this?

[fpgmaas]

@mbyrnepr2 Thanks for the contribution! It seems the deletion of the 3.12-dev CI checks is not picked up properly. Can you try this?

Sorry, turns out the issue was on our side; the 3.12-dev versions were required in the branch protection rules. Modified that now!