Add Laravel 8 support

Author: JeffreyWay

composer.json

@@ -11,7 +11,7 @@
     ],
     "require": {
         "php": ">=5.5.0|>=7.2.5",
-        "illuminate/support": "^5.0|^6.0|^7.0"
+        "illuminate/support": "^5.0|^6.0|^7.0|^8.0"
     },
     "require-dev": {
         "phpspec/phpspec": "~2.0"