build(deps): bump cssnano from 7.1.4 to 7.1.9

Bumps [cssnano](https://github.com/cssnano/cssnano) from 7.1.4 to 7.1.9.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@7.1.4...cssnano@7.1.9)

---
updated-dependencies:
- dependency-name: cssnano
  dependency-version: 7.1.7
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]