[deps] Update channels-redis requirement from ~=4.1.0 to ~=4.2.0

Updates the requirements on [channels-redis](https://github.com/django/channels_redis) to permit the latest version.
- [Changelog](https://github.com/django/channels_redis/blob/main/CHANGELOG.txt)
- [Commits](django/channels_redis@4.1.0...4.2.0)

---
updated-dependencies:
- dependency-name: channels-redis
  dependency-type: direct:production
...

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

requirements-test.txt

@@ -1,5 +1,5 @@
 openwisp-utils[qa,selenium] @ https://github.com/openwisp/openwisp-utils/tarball/master
 django-redis~=5.4.0
 mock-ssh-server~=0.9.1
-channels_redis~=4.1.0
+channels_redis~=4.2.0
 freezegun~=1.5.1