There is a new pull request by newbluemoon against master on the void-packages repository

https://github.com/newbluemoon/void-packages treeline
https://github.com/void-linux/void-packages/pull/26923

treeline: update to 3.1.4
Fixes an incompatibility with Python 3.9, current version 3.8 crashes on startup.

A patch file from https://github.com/void-linux/void-packages/pull/26923.patch is attached