fix namespace and use spelling mistake

apps/backend/app/Http/Controllers/EventsController.php

@@ -1,11 +1,11 @@
 <?php
 
-namespace app\Http\Controllers;
+namespace App\Http\Controllers;
 
-use app\Mail\EventParticipationCancelledMail;
-use app\Models\Event;
-use app\Models\Task;
-use app\Notifications\EventDeleted;
+use App\Mail\EventParticipationCancelledMail;
+use App\Models\Event;
+use App\Models\Task;
+use App\Notifications\EventDeleted;
 use Carbon\Carbon;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Request;