Bump redis from 3.4.1 to 3.5.2

Bumps [redis](https://github.com/andymccurdy/redis-py) from 3.4.1 to 3.5.2.
- [Release notes](https://github.com/andymccurdy/redis-py/releases)
- [Changelog](https://github.com/andymccurdy/redis-py/blob/master/CHANGES)
- [Commits](redis/redis-py@3.4.1...3.5.2)

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

requirements.txt

@@ -37,7 +37,7 @@ pytest-mock==3.1.0        # via -r requirements.in
 pytest==5.4.1             # via -r requirements.in, pytest-cov, pytest-mock
 python-dateutil==2.7.3    # via croniter
 pytz==2019.3              # via -r requirements.in, babel
-redis==3.4.1              # via -r requirements.in
+redis==3.5.2              # via -r requirements.in
 requests==2.23.0          # via sphinx
 six==1.11.0               # via more-itertools, packaging, pip-tools, python-dateutil
 snowballstemmer==2.0.0    # via sphinx