gotta use the rc branch as the feature is still in beta

Author: themsaid

composer.json

@@ -37,7 +37,7 @@
         "illuminate/notifications": "^5.3@dev",
         "illuminate/queue": "^5.3@dev",
         "illuminate/support": "^5.3@dev",
-        "pusher/pusher-php-server": "^2.4.0"
+        "pusher/pusher-php-server": "2.5.0-rc4"
     },
     "require-dev": {
         "mockery/mockery": "^0.9.5",