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

https://github.com/toluschr/void-packages add-mlpack
https://github.com/void-linux/void-packages/pull/20154

New package: mlpack-3.2.2
If #20153 gets merged, the `makedepends` variable needs to be changed.

A patch file from https://github.com/void-linux/void-packages/pull/20154.patch is attached