Bump webpack-dev-server from 4.7.3 to 4.7.4 (#334)

Bump webpack-dev-server from 4.7.3 to 4.7.4 (#334)

Bumps [webpack-dev-server](https://github.com/webpack/webpack-dev-server) from 4.7.3 to 4.7.4.
- [Release notes](https://github.com/webpack/webpack-dev-server/releases)
- [Changelog](https://github.com/webpack/webpack-dev-server/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack/webpack-dev-server/compare/v4.7.3...v4.7.4)

---
updated-dependencies:
- dependency-name: webpack-dev-server
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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