chore(deps-dev): bump postcss-custom-media from 7.0.8 to 8.0.0

Bumps [postcss-custom-media](https://github.com/postcss/postcss-custom-media) from 7.0.8 to 8.0.0.
- [Release notes](https://github.com/postcss/postcss-custom-media/releases)
- [Changelog](https://github.com/postcss/postcss-custom-media/blob/master/CHANGELOG.md)
- [Commits](csstools/postcss-custom-media@7.0.8...8.0.0)

---
updated-dependencies:
- dependency-name: postcss-custom-media
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>