refactor: support php 8

Author: ibrunotome

composer.json

@@ -9,7 +9,7 @@
         }
     ],
     "require": {
-        "php" : "^7.0"
+        "php" : "^7.0 || ^8.0"
     },
     "require-dev": {
         "illuminate/support": "~5.1.0|~5.2.0|~5.3.0|~5.4.0|~5.5.0|~5.6.0|~5.7.0",