Prepare release v308 (heroku#1594)

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]
 
+
+## [v308] - 2025-05-15
+
 - Removed support for Ubuntu 20.04 (and thus Heroku-20 / `heroku/builder:20`). This includes removing support for Ruby < 3.1 and Bundler < 2.3. (https://github.com/heroku/buildpacks-ruby/pull/1591)
 
 ## [v307] - 2025-05-14
@@ -1700,7 +1703,8 @@ 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/v307...main
+[unreleased]: https://github.com/heroku/heroku-buildpack-ruby/compare/v308...main
+[v308]: https://github.com/heroku/heroku-buildpack-ruby/compare/v307...v308
 [v307]: https://github.com/heroku/heroku-buildpack-ruby/compare/v306...v307
 [v306]: https://github.com/heroku/heroku-buildpack-ruby/compare/v305...v306
 [v305]: https://github.com/heroku/heroku-buildpack-ruby/compare/v304...v305

lib/language_pack/version.rb

@@ -2,6 +2,6 @@
 
 module LanguagePack
   class LanguagePack::Base
-    BUILDPACK_VERSION = "v307"
+    BUILDPACK_VERSION = "v308"
   end
 end