Update postgres Docker tag to v13.20

webserver/docker_keycloak/templates/docker-compose.yml

@@ -33,7 +33,7 @@ services:
 
   db:
 
-    image: postgres:13.6
+    image: postgres:13.20
     restart: always
     volumes:
       - /srv/keycloak/db:/var/lib/postgresql/data