build(deps): bump redis from 5.2.1 to 6.1.0 in /backend (#2638)

Bumps [redis](https://github.com/redis/redis-py) from 5.2.1 to 6.1.0.
- [Release notes](https://github.com/redis/redis-py/releases)
- [Changelog](https://github.com/redis/redis-py/blob/master/CHANGES)
- [Commits](redis/redis-py@v5.2.1...v6.1.0)

---
updated-dependencies:
- dependency-name: redis
  dependency-version: 6.1.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

backend/requirements.txt

@@ -8,6 +8,6 @@ google-cloud-storage==2.18.2
 gunicorn==23.0.0
 python-dateutil==2.9.0.post0
 pytoml==0.1.21
-redis==5.2.1
+redis==6.1.0
 swagger-ui-bundle==1.1.0
 zstandard==0.23.0