Add changelog entry for contacted_at

CHANGELOG

@@ -17,6 +17,9 @@ v 8.2.0 (unreleased)
   - Remove deprecated CI events from project settings page
   - Use issue editor as cross reference comment author when issue is edited with a new mention.
 
+v 8.1.3
+  - Spread out runner contacted_at updates
+
 v 8.1.1
   - Fix cloning Wiki repositories via HTTP (Stan Hu)
   - Add migration to remove satellites directory