Bump cssnano from 7.0.6 to 7.1.1

Bumps [cssnano](https://github.com/cssnano/cssnano) from 7.0.6 to 7.1.1.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@7.0.6...cssnano@7.1.1)

---
updated-dependencies:
- dependency-name: cssnano
  dependency-version: 7.1.1
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]