Add six 1.12.0 to the list of compatible dependencies

[n1lanjan]

Current compatible versions: six<=1.11.0,>=1.7.0

[rmk135]

Hi there,

Thanks for the request, I’ll work on it on weekends.

Roman

[rmk135]

Done at 3.14.3 with a bunch of other fixes.

Release is already pypiized, so u're welcome to update.