build: align package.nix with nixpkgs version; verbatim copy

[blaggacao]

This aims to reduce confusion for people who more closely want to track the pimalaya project in their nixos convfigurations with overlays.

[soywod]

Now that the derivation is up-to-date on nixpkgs, I would rather delete package.nix and update default.nix to use the nixpkgs derivation instead of a local package.nix. I will give it a shot whenever I can. Thanks for pointing it out!

[blaggacao]

Now that the derivation is up-to-date on nixpkgs, I would rather delete package.nix and update default.nix to use the nixpkgs derivation instead of a local package.nix.

That seems like a good idea, indeed! — I got my setup working, but I still needed to research a while into how building all the things I needed. Having nixpkgs be the authoritative origin for v1+ packages seems like equally useful.