refactor: 修改自动写入时间的格式为在数据库配置文件配置

app/admin/model/v1/AttachmentModel.php

@@ -16,8 +16,6 @@ class AttachmentModel extends AttachmentBaseModel
     use SoftDelete;
     // 软删除字段
     protected $deleteTime = 'deleted_at';
-    // 自动写入时间格式
-    protected $autoWriteTimestamp = 'datetime';
 
     // JSON字段
     protected $json = ['attach'];