Bump postcss-cli from 7.1.0 to 7.1.1 in /assets

Bumps [postcss-cli](https://github.com/postcss/postcss-cli) from 7.1.0 to 7.1.1.
- [Release notes](https://github.com/postcss/postcss-cli/releases)
- [Changelog](https://github.com/postcss/postcss-cli/blob/master/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss-cli/compare/7.1.0...7.1.1

)

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