Prepare release v320 (heroku#1642)

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]
 
+
+## [v320] - 2025-09-09
+
 - Set `export PUMA_PERSISTENT_TIMEOUT=95` to match recommended router 2.0 settings (https://github.com/heroku/heroku-buildpack-ruby/pull/1641)
 
 ## [v319] - 2025-08-27
@@ -1755,7 +1758,8 @@ 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/v319...main
+[unreleased]: https://github.com/heroku/heroku-buildpack-ruby/compare/v320...main
+[v320]: https://github.com/heroku/heroku-buildpack-ruby/compare/v319...v320
 [v319]: https://github.com/heroku/heroku-buildpack-ruby/compare/v318...v319
 [v318]: https://github.com/heroku/heroku-buildpack-ruby/compare/v317...v318
 [v317]: https://github.com/heroku/heroku-buildpack-ruby/compare/v316...v317

lib/language_pack/version.rb

@@ -2,6 +2,6 @@
 
 module LanguagePack
   class LanguagePack::Base
-    BUILDPACK_VERSION = "v319"
+    BUILDPACK_VERSION = "v320"
   end
 end