Move registry fix Changelog entry to valid version

CHANGELOG

@@ -2,6 +2,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.8.1 (unreleased)
   - Fix MySQL compatibility in zero downtime migrations helpers
+  - Fix the CI login to Container Registry (the gitlab-ci-token user)
 
 v 8.8.0 (unreleased)
   - Implement GFM references for milestones (Alejandro Rodríguez)
@@ -32,7 +33,6 @@ v 8.8.0 (unreleased)
   - Bump mail_room to 0.7.0 to fix stuck IDLE connections
   - Remove future dates from contribution calendar graph.
   - Support e-mail notifications for comments on project snippets
-  - Fix the CI login to Container Registry (the gitlab-ci-token user)
   - Fix API leak of notes of unauthorized issues, snippets and merge requests
   - Use ActionDispatch Remote IP for Akismet checking
   - Fix error when visiting commit builds page before build was updated