I'll chime in here, as I was also a bit confused when exploring the GitHub, Heptapod, PyPi and the project's documentation.
It seems that the newest version of the library on PyPi is, as of the time of writing this, 3.1.5. The documentation linked in PyPi and Heptapod, however, marks "Stable" as 3.1.3 and "Latest" as 3.1.4.
I'm a bit more cautious after what happened to Axios, so I gotta' ask - is 3.1.5 the current "stable" release? If so, could we also mark that in the docs?
Thanks for your time and the great work you've been putting out.
Have a great one!
Robert.