Regenerate cargo dependencies for v0.28

[NthTensor]

Thanks for the awesome flake! I'm on NixOS and am trying to update this to support Gleam v0.28. Seems like I need to update the dependencies but I'm not exactly sure what to do with the output of make generate.

If you give me some direction I can open a PR.

[vic]

make generate modifies the Cargo.nix file from gleam dependencies. I just updated it and also had to upgrade the nixpkgs version being used and the rust compiler version to latest stable. See #3

[NthTensor]

Thanks so much!