Merge pull request #4 from shalvah/dependabot/composer/pusher/pusher-php-server-tw-4.0

Update pusher/pusher-php-server requirement from ^3.0 to ^4.0

Author: shalvah

composer.json

@@ -18,7 +18,7 @@
   ],
   "require": {
     "php": "^7.1",
-    "pusher/pusher-php-server": "^3.0",
+    "pusher/pusher-php-server": "^4.0",
     "monolog/monolog": "^1.23"
   },
   "autoload": {