build(deps-dev): bump cssnano from 7.0.2 to 7.0.3 in /csfieldguide

Bumps [cssnano](https://github.com/cssnano/cssnano) from 7.0.2 to 7.0.3.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@7.0.2...cssnano@7.0.3)

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

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

Author: dependabot[bot]