Add Changelog entry for the fix for the health_check access token changing

CHANGELOG

@@ -16,6 +16,7 @@ v 8.9.0 (unreleased)
 v 8.8.3
   - Fix gitlab importer failing to import new projects due to missing credentials
   - Fix import URL migration not rescuing with the correct Error
+  - Fix health check access token changing due to old application settings being used
 
 v 8.8.2
   - Added remove due date button. !4209