移除无效配置参数

config/admin.php

@@ -85,14 +85,6 @@ return [
    */
     'assets_server' => env('ADMIN_ASSETS_SERVER'),
 
-    /*
-    |--------------------------------------------------------------------------
-    | Cdn setting
-    |--------------------------------------------------------------------------
-    |
-   */
-    'cdn' => env('ADMIN_CDN', false),
-
     /*
     |--------------------------------------------------------------------------
     | Access via `https`