Make package ready for Laravel 6

Author: stefanbauer

composer.json

@@ -17,7 +17,7 @@
     ],
     "require": {
         "php" : "^7.0",
-        "illuminate/support": "~5.5.0|~5.6.0|~5.7.0|~5.8.0",
+        "illuminate/support": "~5.5.0|~5.6.0|~5.7.0|~5.8.0|^6.0",
         "graham-campbell/guzzle-factory": "^3.0"
     },
     "require-dev": {