allow symfony 5

Author: Jeroeny

composer.json

@@ -10,7 +10,7 @@
         "enqueue/enqueue": "^0.9",
         "queue-interop/amqp-interop": "^0.8",
         "queue-interop/queue-interop": "^0.7|^0.8",
-        "symfony/config": "^3.4|^4"
+        "symfony/config": "^3.4|^4|^5"
     },
     "require-dev": {
         "phpunit/phpunit": "~5.5",