Prepare release v313

[heroku-linguist]

Commits since the last release:

• Switch from GPG to Sigstore for Python source verification (Switch from GPG to Sigstore for Python source verification #1924)
• Stop compiling Python using --with-system-expat (Stop compiling Python using --with-system-expat #1925)
• Add support for Python 3.14 (Add support for Python 3.14 #1927)
• Add support for Python 3.13.8 (Add support for Python 3.13.8 #1928)
• Add support for Python 3.12.12, 3.11.14, 3.10.19, 3.9.24 (Add support for Python 3.12.12, 3.11.14, 3.10.19, 3.9.24 #1929)

For the full diff, see the compare view:
v312...main

[edmorley]

$ make publish
Checking environment...
Checking buildpack versions in sync...
Extracting changelog entry for this release...

- Added support for Python 3.14. ([#1927](https://github.com/heroku/heroku-buildpack-python/pull/1927))
- The Python 3.13 version alias now resolves to Python 3.13.8. ([#1928](https://github.com/heroku/heroku-buildpack-python/pull/1928))
- The Python 3.12 version alias now resolves to Python 3.12.12. ([#1929](https://github.com/heroku/heroku-buildpack-python/pull/1929))
- The Python 3.11 version alias now resolves to Python 3.11.14. ([#1929](https://github.com/heroku/heroku-buildpack-python/pull/1929))
- The Python 3.10 version alias now resolves to Python 3.10.19. ([#1929](https://github.com/heroku/heroku-buildpack-python/pull/1929))
- The Python 3.9 version alias now resolves to Python 3.9.24. ([#1929](https://github.com/heroku/heroku-buildpack-python/pull/1929))
- Stopped using `--with-system-expat` when compiling new Python versions. ([#1925](https://github.com/heroku/heroku-buildpack-python/pull/1925))

Deploy as v313 [y/n]? y

Creating GitHub release...
https://github.com/heroku/heroku-buildpack-python/releases/tag/v313

Publishing to the Heroku Buildpack Registry...
Two-factor code: ********************************************
 ›   Error: Could not publish 'heroku/python': 423, {"id":"ctc_denied","error":"Negative 
 ›   response from CTC for request: 
...

$ heroku buildpacks:publish heroku/python v313
Two-factor code: ********************************************
Publishing buildpack heroku/python... done
Publishing buildpack was successful
$ heroku buildpacks:versions heroku/python | head -n 3
 Version Released At              Status    
 ─────── ──────────────────────── ───────── 
 313     2025-10-09T20:32:33.639Z published