Add postgresql to list of docker images to pull

PROD-31435

Change-Id: I68f323f8238bbb07509a0ea6b58694d46608c412
diff --git a/docker/swarm/stack/postgresql.yml b/docker/swarm/stack/postgresql.yml
index 619e0c2..12eb874 100644
--- a/docker/swarm/stack/postgresql.yml
+++ b/docker/swarm/stack/postgresql.yml
@@ -9,6 +9,8 @@
     postgresql_admin_user: postgres
   docker:
     client:
+      images:
+        - ${_param:docker_image_postgresql}
       stack:
         postgresql:
           environment: