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

xbps-src: add purge-binpkgs action
https://github.com/void-linux/void-packages/pull/48715

Description:
gets rid of binpkgs that don't match what's in srcpkgs/ (different version or missing) and cleans all repodatas.

WIP: need to document this better

#### Testing the changes
- I tested the changes in this PR: **briefly**