[deps] Update django-redis requirement from ~=5.4.0 to ~=6.0.0

Updates the requirements on [django-redis](https://github.com/jazzband/django-redis) to permit the latest version.
- [Release notes](https://github.com/jazzband/django-redis/releases)
- [Changelog](https://github.com/jazzband/django-redis/blob/master/CHANGELOG.rst)
- [Commits](jazzband/django-redis@5.4.0...6.0.0)

---
updated-dependencies:
- dependency-name: django-redis
  dependency-version: 6.0.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements-test.txt

@@ -5,4 +5,4 @@ openwisp-monitoring @ https://github.com/openwisp/openwisp-monitoring/tarball/1.
 openwisp-controller @ https://github.com/openwisp/openwisp-controller/tarball/1.2
 openwisp-utils[qa,selenium,channels-test] @ https://github.com/openwisp/openwisp-utils/tarball/1.2
 redis~=6.2.0
-django_redis~=5.4.0
+django_redis~=6.0.0