bug#31088: Use '@' as version number separator in guix output

[Ludovic Courtès]

Hey Chris,

Chris Marusich <cmmarus...@gmail.com> skribis:

> I've committed this as ede121de426f9c56820852888a0b370f0ccbce49 on the
> master branch.  If anything breaks on Hydra or elsewhere, please don't
> hesitate to revert it.

Awesome, thank you!

Ludo’.