Bump cssnano from 4.1.10 to 4.1.11 in /etp-public

Bumps [cssnano](https://github.com/cssnano/cssnano) from 4.1.10 to 4.1.11.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](cssnano/cssnano@v4.1.10...v4.1.11)

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

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