There is an updated pull request by ahesford against master on the void-packages repository

https://github.com/ahesford/void-packages python
https://github.com/void-linux/void-packages/pull/25413

[WIP] Python 3.9
I've moved `python3` and `python3-tkinter` to 3.9.0 and revbumped the 1109 packages that either have an shlib dependency on `python3` or installs files to `usr/lib/python3.8/site-packages`. Of these, I dropped `noarch` from 411 packages.

I'll start build-testing on `x86_64` to identify breakage and report back with problems. In the meantime, anybody with excess computing resources can feel free to try building for other archs.

A patch file from https://github.com/void-linux/void-packages/pull/25413.patch is attached