databases/py-redis: Update to 3.2.1

• Switch MASTER_SITES back to PyPI as it's the preferred way for Python ports and all relevant files are supplied with the sdist.

• Sort variables according to the PHB by moving the OPTIONS block further down.

Changelog:

https://github.com/andymccurdy/redis-py/blob/3.2.1/CHANGES

Info about backwards incompatible changes since 3.0.0:

https://github.com/andymccurdy/redis-py/blob/3.2.1/CHANGES#L72

PR: 237237
Submitted by: koobs (maintainer)
Reported by: sunpoet
Approved by: koobs (maintainer)