support Laravel 5.6

Author: jijoel

composer.json

@@ -27,7 +27,7 @@
     ],
     "minimum-stability": "dev",
     "require": {
-        "illuminate/support": "5.2.x|5.3.x|5.4.x|5.5.x"
+        "illuminate/support": "^5.2"
     },
     "extra": {
         "laravel": {