build(deps): bump postcss-selector-parser from 6.0.7 to 6.0.8

Bumps [postcss-selector-parser](https://github.com/postcss/postcss-selector-parser) from 6.0.7 to 6.0.8.
- [Release notes](https://github.com/postcss/postcss-selector-parser/releases)
- [Changelog](https://github.com/postcss/postcss-selector-parser/blob/master/CHANGELOG.md)
- [Commits](postcss/postcss-selector-parser@v6.0.7...v6.0.8)

---
updated-dependencies:
- dependency-name: postcss-selector-parser
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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