fix: HotModuleReplacementPlugin 제거

[prefer2]

구현 사항

• 불필요한 HotModuleReplacementPlugin를 제거했습니다.

  Since webpack-dev-server v4, HMR is enabled by default. It automatically applies webpack.HotModuleReplacementPlugin which is required to enable HMR. So you don't have to add this plugin to your webpack.config.js when hot is set to true in config or via the CLI option --hot. See the HMR concepts page for more information.

• 참고자료: https://webpack.js.org/configuration/dev-server/#devserverhot

closed #636