!822 删除未生效代码

Merge pull request !822 from mrzxc/fixbug/unuseCodeDelete

@@ -123,12 +123,7 @@ module.exports = {
               }
             }
           })
-
-          config.optimization.runtimeChunk('single'),
-          {
-             from: path.resolve(__dirname, './public/robots.txt'), //防爬虫文件
-             to: './' //到根目录下
-          }
+          config.optimization.runtimeChunk('single')
     })
   }
 }