fix defining column key fluently

Author: pxpm

src/app/Library/CrudPanel/CrudColumn.php

@@ -89,7 +89,7 @@ public function key(string $key)
         }
 
         $this->attributes = $column;
-        $this->setOperationSetting('columns', array_merge($columns, [$key => $column]));
+        $this->crud()->setOperationSetting('columns', array_merge($columns, [$key => $column]));
 
         return $this;
     }