fix namespace and use spelling mistake

apps/backend/app/Notifications/EventDeleted.php

@@ -1,8 +1,8 @@
 <?php
 
-namespace app\Notifications;
+namespace App\Notifications;
 
-use app\Models\Event;
+use App\Models\Event;
 use Illuminate\Bus\Queueable;
 use Illuminate\Contracts\Broadcasting\ShouldBroadcast;
 use Illuminate\Notifications\Messages\BroadcastMessage;