[FEATURE REQUEST] Add nh development version to nix-community cachix

[Jackaed]

For those of us using the development version of cachix, it would be nice for the nh build artifacts to be cached on the nix-community cachix, to prevent us from having to compile it from source locally, should we want to not use the nixpkgs version.

[NotAShelf]

I'm not exactly sure why it's not being cached; nh is in the buildbot list of nix-community infrastructure, so I was under the impression that it should be cached. I'll ask about it later.