chore(deps-dev): bump stylelint-config-standard from 20.0.0 to 21.0.0

Bumps [stylelint-config-standard](https://github.com/stylelint/stylelint-config-standard) from 20.0.0 to 21.0.0.
- [Release notes](https://github.com/stylelint/stylelint-config-standard/releases)
- [Changelog](https://github.com/stylelint/stylelint-config-standard/blob/master/CHANGELOG.md)
- [Commits](stylelint/stylelint-config-standard@20.0.0...21.0.0)

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