调整图片上传校验

app/Admin/Controllers/Article/IndexController.php

@@ -67,7 +67,7 @@ class IndexController extends AdminController
         $form->text('rank', '职称')->help('领导班子需要添加此数据');
 
         $form->image('cover', '封面')
-            ->rules('mimes:jpeg,jpg,png')
+            ->rules('image|mimes:jpeg,jpg,png')
             ->move('images/'.date('Y/m/d'))
             ->removable()
             ->uniqueName();