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

https://github.com/anjandev/void-packages xtools
https://github.com/void-linux/void-packages/pull/21706

xtools: added spdx-licenses-list for linting license field
See: https://github.com/leahneukirchen/xtools/issues/180#issuecomment-624752073

@Chocimier 

A patch file from https://github.com/void-linux/void-packages/pull/21706.patch is attached