Prepare release v254

[heroku-linguist]

Commits since the last release:

• Update CI to Ubuntu 24.04 runner images (Update CI to Ubuntu 24.04 runner images #1610)
• Bump setuptools from 69.2.0 to 70.3.0 (Bump setuptools from 69.2.0 to 70.3.0 #1614)
• Bump pipenv from 2023.12.1 to 2024.0.1 (Bump pipenv from 2023.12.1 to 2024.0.1 #1601)

For the full diff, see the compare view:
v253...main

[edmorley]

$ make publish
Deploy as version: v254 [y/n]? y

Tagging commit 9a3b9074a95d6c68fae14a3c6a132687b36146e0 with v254... 
Total 0 (delta 0), reused 0 (delta 0), pack-reused 0
To https://github.com/heroku/heroku-buildpack-python
 * [new tag]         v254 -> v254

Publishing to the buildpack registry...
Two-factor code: ********************************************
Publishing buildpack heroku/python... done
Publishing buildpack was successful

 Version Released At              Status    
 ─────── ──────────────────────── ───────── 
 254     2024-07-16T09:58:15.934Z published