Don't publish MySQL port

docker-compose.yml

@@ -7,8 +7,6 @@ services:
     command: --max_allowed_packet=256M
     volumes:
       - "./data/db:/var/lib/mysql:delegated"
-    ports:
-       - "3306:3306"
     environment:
       MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD}
       MYSQL_DATABASE: ${MYSQL_DATABASE}