build(deps): bump posthtml-postcss from 1.0.2 to 1.0.3

Bumps [posthtml-postcss](https://github.com/posthtml/posthtml-postcss) from 1.0.2 to 1.0.3.
- [Release notes](https://github.com/posthtml/posthtml-postcss/releases)
- [Changelog](https://github.com/posthtml/posthtml-postcss/blob/master/CHANGELOG.md)
- [Commits](posthtml/posthtml-postcss@v1.0.2...v1.0.3)

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

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