Replace redistimeseries-py with the latest redis-py 4.x

[ajeetraina]

The redistimeseries-py is deprecated , hence the tutorial https://developer.redis.com/howtos/redistimeseries/using-python#step-7installation needs to be updated with the latest redis-py 4.x.

Reference: https://redis-py.readthedocs.io/en/stable/redismodules.html#redistimeseries-commands

[ajeetraina]

Raised PR:#308 for the same.

[ajeetraina]

Updated the doc.