Prepare release v351 (heroku#1723)

* Prepare release v351

* Update CHANGELOG.md

Removed the v350 entry as it mistakenly cited Ruby 3.3.9 instead of Ruby 3.4.9. The changelog entry is superficial so there's no actual code difference between the v350 and v351 versions published to the buildpack registry.

Signed-off-by: Colin Casey <casey.colin@gmail.com>

---------

Signed-off-by: Colin Casey <casey.colin@gmail.com>
Co-authored-by: heroku-linguist[bot] <136119646+heroku-linguist[bot]@users.noreply.github.com>
Co-authored-by: Colin Casey <casey.colin@gmail.com>

Author: heroku-linguist[bot]

CHANGELOG.md

@@ -3,9 +3,9 @@
 ## [Unreleased]
 
 
-## [v350] - 2026-03-11
+## [v351] - 2026-03-11
 
-- Ruby 3.3.9 is now available
+- Ruby 3.4.9 is now available
 
 
 ## [v349] - 2026-03-06
@@ -1916,7 +1916,8 @@ Bugfixes:
 * Change gem detection to use lockfile parser
 * use `$RACK_ENV` when thin is detected for rack apps
 
-[unreleased]: https://github.com/heroku/heroku-buildpack-ruby/compare/v350...main
+[unreleased]: https://github.com/heroku/heroku-buildpack-ruby/compare/v351...main
+[v351]: https://github.com/heroku/heroku-buildpack-ruby/compare/v350...v351
 [v350]: https://github.com/heroku/heroku-buildpack-ruby/compare/v349...v350
 [v349]: https://github.com/heroku/heroku-buildpack-ruby/compare/v348...v349
 [v348]: https://github.com/heroku/heroku-buildpack-ruby/compare/v347...v348