Fixes default maintenance driver on config stub (#50052)

Author: nunomaduro

config-stubs/app.php

@@ -145,7 +145,7 @@
     */
 
     'maintenance' => [
-        'driver' => env('APP_MAINTENANCE_DRIVER', 'cache'),
+        'driver' => env('APP_MAINTENANCE_DRIVER', 'file'),
         'store' => env('APP_MAINTENANCE_STORE', 'database'),
     ],