chore(deps-dev): bump postcss from 8.4.20 to 8.4.31 (#47)

Bumps [postcss](https:/postcss/postcss) from 8.4.20 to 8.4.31.
- [Release notes](https:/postcss/postcss/releases)
- [Changelog](https:/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.20...8.4.31)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>