Merge pull request #52 from laravel-notification-channels/php-version

Limited highest PHP version to patch release of 8.1

composer.json

@@ -12,7 +12,7 @@
         }
     ],
     "require": {
-        "php": ">=7.3",
+        "php": "^7.3 | ~8.0.0 | ~8.1.0",
         "guzzlehttp/guzzle": "^6.2 || ^7.0",
         "illuminate/notifications": "~5.5 || ~6.0 || ~7.0 || ~8.0",
         "illuminate/support": "~5.5 || ~6.0 || ~7.0 || ~8.0"