Updating Symfony compatibility to include 5.x

Author: stefantalen

Diff for: composer.json

@@ -11,8 +11,8 @@
     ],
     "require": {
         "php": ">=5.4.16",
-        "symfony/validator": ">=2.8",
-        "symfony/framework-bundle": ">=2.8"
+        "symfony/validator": "^2.8|^3.0|^4.0|^5.0",
+        "symfony/framework-bundle": "^2.8|^3.0|^4.0|^5.0"
     },
     "autoload": {
         "psr-4": {