Run a nightly build with AVX-512 emulation

[cmb69]

Description

This has been suggested in #15159 by @Disservin, and seems to be a reasonable thing to do, given that at least current GH runners do not support AVX-512. And even if performance is slow (might take twice as long), a single or maybe two nightly jobs should be okay.

Given that is not really related to #15159, especially since #15301 has been merged, I'm dropping this a new feature request.