Try supporting Python 3.6.0
In https://github.com/pandas-dev/pandas/pull/29212, we bumped the minimum Python to 3.6.1. @datapythonista mentioned an issue with 3.6.0 at https://github.com/pandas-dev/pandas/pull/29212#issuecomment-551370118

> Seems like Python 3.6 has something (I guess a bug) causing the error TypeError: only integer scalar arrays can be converted to a scalar index when converting strings to bytes in some of our cases.

I vaguely recall a few issues with 0.25.x requiring a point release of python 3.5. We should see if we can support 3.6.0 to save some headaches down the road.