fix namespace and use spelling mistake

apps/backend/app/Providers/AppServiceProvider.php

@@ -1,11 +1,11 @@
 <?php
 
-namespace app\Providers;
+namespace App\Providers;
 
-use app\Models\Event;
-use app\Models\User;
-use app\Observers\EventObserver;
-use app\Observers\UserObserver;
+use App\Models\Event;
+use App\Models\User;
+use App\Observers\EventObserver;
+use App\Observers\UserObserver;
 use Illuminate\Support\Facades\Route;
 use Illuminate\Support\ServiceProvider;