restart buildbot when database has changed

tasks/database.yaml

@@ -6,11 +6,13 @@
       postgresql_user:
         name: "{{buildbot_db_user}}"
         password: "{{buildbot_db_pass}}"
+      notify: restart buildbot service
 
     - name: postgresql database
       postgresql_db:
         name: "{{buildbot_db_name}}"
         owner: "{{buildbot_db_user}}"
+      notify: restart buildbot service
 
   become: true
   become_user: postgres