refs(py3): Bump hiredis for python 3.6 support. (#19676)
hiredis 0.3.1 supports Python 3.6/3.7, so testing bumping. 1.0.0 has a breaking change, although I'm
not sure how bad this is. https://github.com/redis/hiredis-py/pull/82 is the change, and it
basically implements strict unicode decoding errors, which I assume we'd prefer rather than silently
converting values. So we could potentially ugrade to latest if we think this is ok. Not sure how
we'd validate this tbqh.