Prepare release v6.3.0

## heroku/python

### Changed

- The Python 3.14 version alias now resolves to Python 3.14.4. ([#548](#548))
- The Python 3.13 version alias now resolves to Python 3.13.13. ([#548](#548))
- The forbidden env vars check now reports all forbidden env vars found rather than only the first. ([#542](#542))
- The forbidden env vars check now checks for known problematic Poetry env vars too. ([#542](#542))

Author: heroku-linguist[bot]

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [6.3.0] - 2026-04-07
+
 ### Changed
 
 - The Python 3.14 version alias now resolves to Python 3.14.4. ([#548](https://github.com/heroku/buildpacks-python/pull/548))
@@ -621,7 +623,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Initial implementation. ([#3](https://github.com/heroku/buildpacks-python/pull/3))
 
-[unreleased]: https://github.com/heroku/buildpacks-python/compare/v6.2.0...HEAD
+[unreleased]: https://github.com/heroku/buildpacks-python/compare/v6.3.0...HEAD
+[6.3.0]: https://github.com/heroku/buildpacks-python/compare/v6.2.0...v6.3.0
 [6.2.0]: https://github.com/heroku/buildpacks-python/compare/v6.1.0...v6.2.0
 [6.1.0]: https://github.com/heroku/buildpacks-python/compare/v6.0.1...v6.1.0
 [6.0.1]: https://github.com/heroku/buildpacks-python/compare/v6.0.0...v6.0.1

buildpack.toml

@@ -2,7 +2,7 @@ api = "0.10"
 
 [buildpack]
 id = "heroku/python"
-version = "6.2.0"
+version = "6.3.0"
 name = "Heroku Python"
 homepage = "https://github.com/heroku/buildpacks-python"
 description = "Heroku's buildpack for Python applications."