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)
- [Commits](https://github.com/webpack/webpack-dev-server/commits/v3.1.5

)

Signed-off-by: dependabot[bot] <support@dependabot.com>