Try to use nix in the deploy and publish CI

[filipeom]

It should be similar to the one Léo did here: https://github.com/formalsec/smtml/blob/main/.github/workflows/build-nix.yml

See if there is a way to specify devDependencies in nix for opam-publish and git-cliff

[redianthus]

You can simply add packages when running the shell with nix-shell -p git-cliff for instance