Adding doctrine orm to dev section

Author: Holger Lösken

composer.json

@@ -27,6 +27,7 @@
         "symfony/serializer": "^4.0 || ^5.0"
     },
     "require-dev": {
+        "doctrine/orm": "^2.9",
         "friendsofphp/php-cs-fixer": "^3.0",
         "jms/serializer-bundle": "^3.0",
         "nyholm/psr7": "^1.3",