Added Symfony5 compatibility

Author: DonCallisto

composer.json

@@ -20,7 +20,7 @@
         "php":          ">=5.3.2",
         "behat/behat":  "^3.0.5",
         "behat/mink":   "^1.5",
-        "symfony/config": "^2.7|^3.0|^4.0"
+        "symfony/config": "^2.7|^3.0|^4.0|^5.0"
     },
 
     "require-dev": {