There's a merged pull request on the void-packages repository

etckeeper: update to 1.18.21, support xbps, run tests
https://github.com/void-linux/void-packages/pull/42192

Description:
- I tested the changes in this PR: yes
- I built this PR locally for my native architecture, (`x86_64-musl`)

A couple of tests fail, likely due to `fakeroot` or similar.