Fix DATABASE_URL

Author: dunglas

doctrine/doctrine-bundle/1.6/manifest.json

@@ -10,7 +10,7 @@
         "#1": "Format described at http://docs.doctrine-project.org/projects/doctrine-dbal/en/latest/reference/configuration.html#connecting-using-a-url",
         "#2": "For an SQLite database, use: \"sqlite:///%kernel.project_dir%/var/data.db\"",
         "#3": "Configure your db driver and server_version in config/packages/doctrine.yaml",
-        "DATABASE_URL": "\"mysql://symfony:password@127.0.0.1:3306/symfony?charset=utf8mb4&serverVersion=5.7\""
+        "DATABASE_URL": "mysql://symfony:password@db:3306/symfony?charset=utf8mb4&serverVersion=5.7"
     },
     "dockerfile": ["RUN docker-php-ext-install pdo_mysql"],
     "docker-compose": {