Laravel 8 support (#9)

Author: Cannonb4ll

composer.json

@@ -14,8 +14,8 @@
     "require": {
         "php": ">=7.2",
         "guzzlehttp/guzzle": "^6.3 || ^7.0",
-        "illuminate/notifications": "~5.5 || ~6.0 || ~7.0",
-        "illuminate/support": "~5.5 || ~6.0 || ~7.0"
+        "illuminate/notifications": "~5.5 || ~6.0 || ~7.0 || ^8.0",
+        "illuminate/support": "~5.5 || ~6.0 || ~7.0 || ^8.0"
     },
     "require-dev": {
         "mockery/mockery": "^1.2.3",