Bump redis from 4.4.4 to 4.6.0 (#552)

Bumps [redis](https://github.com/redis/redis-py) from 4.4.4 to 4.6.0.
- [Release notes](https://github.com/redis/redis-py/releases)
- [Changelog](https://github.com/redis/redis-py/blob/master/CHANGES)
- [Commits](redis/redis-py@v4.4.4...v4.6.0)

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

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

requirements.txt

@@ -24,7 +24,7 @@ django-sendgrid-v5==1.1.0
 psycopg2-binary==2.9.5
 # Having problems deploying to Heroku with 1.6.3
 pylibmc==1.6.2
-redis==4.4.4
+redis==4.6.0
 rollbar==0.16.3
 
 # web server