Add support for Python 3.12.4

[edmorley]

Release announcement:
https://blog.python.org/2024/06/python-3124-released.html

Changelog:
https://docs.python.org/3.12/whatsnew/changelog.html

Binary builds:
https://github.com/heroku/heroku-buildpack-python/actions/runs/9414066018

GUS-W-14846781.

[edmorley]

Updated versions on:
https://devcenter.heroku.com/articles/python-support#specifying-a-python-version
https://devcenter.heroku.com/articles/python-runtimes#selecting-a-runtime

Published changelog entry:
https://devcenter.heroku.com/changelog-items/2902