Fixed regression: Escalation logic is not active.

config/application.rb

@@ -38,6 +38,7 @@ module Zammad
       'observer::_ticket::_ref_object_touch',
       'observer::_ticket::_online_notification_seen',
       'observer::_ticket::_stats_reopen',
+      'observer::_ticket::_escalation_update',
       'observer::_tag::_ticket_history',
       'observer::_user::_ref_object_touch',
       'observer::_user::_ticket_organization',