Support Laravel 8 (#425)

Author: markdegrootnl

composer.json

@@ -13,7 +13,7 @@
     "prefer-stable": true,
     "require": {
         "php": "^7.2",
-        "illuminate/support": "^6.0|^7.0"
+        "illuminate/support": "^6.0|^7.0|^8.0"
     },
     "require-dev": {
         "mockery/mockery": "^1.0",