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

https://github.com/leahneukirchen/void-packages xmlfoo
https://github.com/void-linux/void-packages/pull/43829

libxml2: update to 2.11.2. libxslt: update to 1.1.38. 
Both releases contain security and memory fixes.

There have been issues regarding libxml2 ABI stability, see
https://gitlab.gnome.org/GNOME/libxml2/-/issues/433
https://gitlab.gnome.org/GNOME/libxml2/-/issues/526

I think I got the configure flags properly to make it work still, but some testing is required.

A patch file from https://github.com/void-linux/void-packages/pull/43829.patch is attached