Sync tox.ini configuration with supported Python versions
Sync tox.ini configuration with supported Python versions

Per Travis CI configuration and trove classifiers, Python 3.2 is not
supported. Remove it from tox.ini.

5977862/redis-py,andymccurdy/redis-py,5977862/redis-py,alisaifee/redis-py,andymccurdy/redis-py,mozillazg/redis-py-doc,redis/redis-py,5977862/redis-py,redis/redis-py,andymccurdy/redis-py,alisaifee/redis-py,mozillazg/redis-py-doc