Prepare release v274 (#1733)

Co-authored-by: heroku-linguist[bot] <136119646+heroku-linguist[bot]@users.noreply.github.com>

Author: heroku-linguist[bot]

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## [Unreleased]
 
+
+## [v274] - 2025-01-08
+
 - Added a deprecation warning for Python 3.9. ([#1732](https://github.com/heroku/heroku-buildpack-python/pull/1732))
 - Removed support for Python 3.8. ([#1732](https://github.com/heroku/heroku-buildpack-python/pull/1732))
 - Improved the error messages shown for EOL or unrecognised major Python versions. ([#1732](https://github.com/heroku/heroku-buildpack-python/pull/1732))
@@ -1143,7 +1146,8 @@ Default Python is now latest 2.7.10. Updated pip and Distribute.
 - Setuptools updated to v16.0
 - pip updated to v7.0.1
 
-[unreleased]: https://github.com/heroku/heroku-buildpack-python/compare/v273...main
+[unreleased]: https://github.com/heroku/heroku-buildpack-python/compare/v274...main
+[v274]: https://github.com/heroku/heroku-buildpack-python/compare/v273...v274
 [v273]: https://github.com/heroku/heroku-buildpack-python/compare/v272...v273
 [v272]: https://github.com/heroku/heroku-buildpack-python/compare/v271...v272
 [v271]: https://github.com/heroku/heroku-buildpack-python/compare/v270...v271