Move Changelog for pipeline fix to valid version

CHANGELOG

@@ -3,6 +3,7 @@ Please view this file on the master branch, on stable branches it's out of date.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)
+  - Fix access to Pipelines by Anonymous user
 v 8.8.0 (unreleased)
   - Implement GFM references for milestones (Alejandro Rodríguez)
@@ -25,7 +26,6 @@ v 8.8.0 (unreleased)
   - Updated gitlab_git to 10.1.0
   - GitAccess#protected_tag? no longer loads all tags just to check if a single one exists
   - Reduce delay in destroying a project from 1-minute to immediately
-  - Fix access to Pipelines by Anonymous user
   - Make build status canceled if any of the jobs was canceled and none failed
   - Upgrade Sidekiq to 4.1.2
   - Added /health_check endpoint for checking service status