Bump webpack from 4.20.2 to 4.23.1

Bumps [webpack](https://github.com/webpack/webpack) from 4.20.2 to 4.23.1.
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](webpack/webpack@v4.20.2...v4.23.1)

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

Author: dependabot-support