Bump redis from 2.10.6 to 4.4.4

Bumps [redis](https://github.com/redis/redis-py) from 2.10.6 to 4.4.4.
- [Release notes](https://github.com/redis/redis-py/releases)
- [Changelog](https://github.com/redis/redis-py/blob/master/CHANGES)
- [Commits](redis/redis-py@2.10.6...v4.4.4)

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

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

Author: dependabot[bot]

requirements.txt

@@ -14,7 +14,7 @@ handy==0.7
 honcho==0.6.4
 Jinja2==2.11.3
 psycopg2==2.7.3.2
-redis==2.10.6
+redis==4.4.4
 celery==3.1.17
 tqdm==4.19.5
 requests==2.18.4