Bump python-cas from 1.6.0 to 1.7.1

Bumps [python-cas](https://github.com/python-cas/python-cas) from 1.6.0 to 1.7.1.
- [Release notes](https://github.com/python-cas/python-cas/releases)
- [Changelog](https://github.com/python-cas/python-cas/blob/master/docs/changelog.rst)
- [Commits](python-cas/python-cas@v1.6.0...v1.7.1)

---
updated-dependencies:
- dependency-name: python-cas
  dependency-version: 1.7.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements.txt

@@ -31,7 +31,7 @@ chardet==5.2.0  # requests
 idna==3.11  # requests
 certifi==2025.11.12  # requests, sentry-sdk
 requests==2.32.5
-python-cas==1.6.0
+python-cas==1.7.1
 django-cas-ng==5.0.1
 
 astroid==4.0.2