New review comment by paper42 on void-packages repository

https://github.com/void-linux/void-packages/pull/33661#discussion_r734835595

Comment:
```suggestion
homepage="https://wiki.gnome.org/action/show/Apps/Gthumb"
changelog="https://gitlab.gnome.org/GNOME/gthumb/-/raw/master/NEWS"
distfiles="${GNOME_SITE}/gthumb/${version%.*}/gthumb-${version}.tar.xz"
```