Latest release (0.4.0) installs incompatible version of redis-py

[patricksmith]

The latest released version of this package pins the redis dependency to >=2.1.0. Recently, version 4.0.0 of redis-py was released and introduces some breaking changes for this package.

The latest code in master appropriately pins the redis dependency to "^3.5.3" which would fix the issue.

To get around this, I've needed to pin the redis dependency to "^3.5.3" wherever our code requires redisbloom.