Bump webpack-cli from 4.5.0 to 4.6.0

Bumps [webpack-cli](https://github.com/webpack/webpack-cli) from 4.5.0 to 4.6.0.
- [Release notes](https://github.com/webpack/webpack-cli/releases)
- [Changelog](https://github.com/webpack/webpack-cli/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack/webpack-cli/compare/webpack-cli@4.5.0...webpack-cli@4.6.0

)

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