Bump cssnano from 6.0.2 to 6.0.3

Bumps [cssnano](https://github.com/cssnano/cssnano) from 6.0.2 to 6.0.3.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/[email protected]@6.0.3)

---
updated-dependencies:
- dependency-name: cssnano
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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