fix db container name

tasks/docker/docker.yml

@@ -153,9 +153,9 @@
     name: mastodon_redis-volatile_1
     state: started
 
-- name: Start mastodon_postgresql_1 container
+- name: Start mastodon_db_1 container
   docker_container:
-    name: mastodon_postgresql_1
+    name: mastodon_db_1
     state: started
 
 # CREATE USER mastodon CREATEDB;