Simplify CHANGELOG entry for heroku-20 EOL

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ipmb

CHANGELOG.md

@@ -9,8 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
-* Builds using the `heroku-20` stack will now log a warning that the stack is end-of-life and should be upgraded to `heroku-24`
-* Removed support for `heroku-20` builds (previously required a legacy version of `pack`)
+* Removed support for EOL `heroku-20` builds 
 
 ## [2.5.0] - 2025-10-21