If you installed it similar to these instructions:
https://github.com/HubTou/HubTou/wiki/Installing-a-Luanti-VoxeLibre-server-%26-development-environment-on-FreeBSD

Then look in the folder you downloaded it to, and see what the .tar.gz file has in the file name.

I’m sure there’s a better way. I’ll mess around with it this week and see if I can figure it out.

If you installed it this way:
https://git.minetest.land/VoxeLibre/VoxeLibre/src/branch/master/HOW_TO_PLAY.md

Then it still may have the version number somewhere in the files it downloaded or in Luanti.