Bump webpack-dev-middleware and webpack-dev-server (#75)

Removes [webpack-dev-middleware](https://github.com/webpack/webpack-dev-middleware). It's no longer used after updating ancestor dependency [webpack-dev-server](https://github.com/webpack/webpack-dev-server). These dependencies need to be updated together.


Removes `webpack-dev-middleware`

Updates `webpack-dev-server` from 3.11.3 to 5.0.4
- [Release notes](https://github.com/webpack/webpack-dev-server/releases)
- [Changelog](https://github.com/webpack/webpack-dev-server/blob/master/CHANGELOG.md)
- [Commits](webpack/webpack-dev-server@v3.11.3...v5.0.4)

---
updated-dependencies:
- dependency-name: webpack-dev-middleware
  dependency-type: indirect
- dependency-name: webpack-dev-server
  dependency-type: direct:development
...

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