build: fix default values in startup script for docker

docker-compose.yml

@@ -27,6 +27,7 @@ services:
       - ./logs:/app/logs
     environment:
       MYSQL_HOST: 'db'
+      MYSQL_PORT: '3306'
       MYSQL_USER: 'java'
       MYSQL_PASSWORD: 'password'
       MYSQL_DATABASE: 'netneutrality'