Use the pusher key read from configuration instead of env file

Themes/Adminlte/views/layouts/master.blade.php

@@ -94,7 +94,7 @@
     <script src="{{ Module::asset('notification:js/pusherNotifications.js') }}"></script>
     <script>
         $(".notifications-list").pusherNotifications({
-            pusherKey: '{{ env('PUSHER_KEY') }}',
+            pusherKey: '{{ config('broadcasting.connections.pusher.key') }}',
             loggedInUserId: {{ $currentUser->id }}
         });
     </script>