Bump webpack-cli from 3.3.11 to 3.3.12

Bumps [webpack-cli](https://github.com/webpack/webpack-cli) from 3.3.11 to 3.3.12.
- [Release notes](https://github.com/webpack/webpack-cli/releases)
- [Changelog](https://github.com/webpack/webpack-cli/blob/v3.3.12/CHANGELOG.md)
- [Commits](webpack/webpack-cli@v3.3.11...v3.3.12)

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

Author: dependabot-preview[bot]