Bump cssutils from 2.6.0 to 2.7.1

Bumps [cssutils](https://github.com/jaraco/cssutils) from 2.6.0 to 2.7.1.
- [Release notes](https://github.com/jaraco/cssutils/releases)
- [Changelog](https://github.com/jaraco/cssutils/blob/main/CHANGES.rst)
- [Commits](https://github.com/jaraco/cssutils/compare/v2.6.0...v2.7.1)

---
updated-dependencies:
- dependency-name: cssutils
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -8,7 +8,7 @@ chardet==5.1.0
 click==8.1.3
 cryptography==3.3.2; platform_machine == 'armv7l'
 cryptography==41.0.1; platform_machine != 'armv7l'
-cssutils==2.6.0
+cssutils==2.7.1
 defusedxml==0.7.1
 Flask==2.3.2
 idna==3.4