chore(deps-dev): update webpack-dev-server requirement in /src (#2688)
chore(deps-dev): update webpack-dev-server requirement in /src (#2688)

Updates the requirements on [webpack-dev-server](https://github.com/webpack/webpack-dev-server) to permit the latest version.
- [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/v4.6.0...v4.7.3)

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

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
h5bp/html5-boilerplate,h5bp/html5-boilerplate