Bump redis from 3.3.2 to 3.3.4

Bumps [redis](https://github.com/andymccurdy/redis-py) from 3.3.2 to 3.3.4.
- [Release notes](https://github.com/andymccurdy/redis-py/releases)
- [Changelog](https://github.com/andymccurdy/redis-py/blob/master/CHANGES)
- [Commits](redis/redis-py@3.3.2...3.3.4)

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

requirements-test.txt

@@ -3,4 +3,4 @@ coverage==4.5.4 # pytest-cov
 mirakuru==2.0.1
 port-for==0.4
 pytest==5.0.1
-redis==3.3.2
+redis==3.3.4