✨ Add github workflow to update nix inputs

[arthsmn]

Closes #15. I'm not familiar with this, so feedback is welcome.

[arthsmn]

@ewen-lbh do you have an idea on how to test this?

[ewen-lbh]

Unfortunately CI is notoriously annoying/impossible to test locally 🥲

Apart from running the just script locally, there's not much you can do but commit and try ^^

Let me know when you tested the just recipe locally, i'll merge this in. If it doesn't work on the first try, that's fine

[arthsmn]

Unfortunately CI is notoriously annoying/impossible to test locally 🥲

Apart from running the just script locally, there's not much you can do but commit and try ^^

Let me know when you tested the just recipe locally, i'll merge this in. If it doesn't work on the first try, that's fine

The Justfile addition is fine.