Add doctrine/orm to required vendors

Author: fre5h

composer.json

@@ -25,6 +25,7 @@
         "php": ">=7.1.3",
         "doctrine/doctrine-bundle": "^1.6.10",
         "doctrine/common": "^2.8",
+        "doctrine/orm": "~2.4",
         "symfony/config": "^4.0",
         "symfony/dependency-injection": "^4.0",
         "symfony/doctrine-bridge": "^4.0",