shell.nix: include gh in the default shell

[SigmaSquadron]

GitHub's CLI is now used by nixpkgs-review to fetch Nixpkgs evaluation results from GitHub Actions. Including it in the default shell will allow all contributors to easily log-in to GitHub when nixpkgs-review tries to fetch evaluation results.

Spawned from a small discussion in the dev matrix channel about adding a Justfile to Nixpkgs. Adding just gh to the shell for now should be considerably less controversial.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

---

Add a 👍 reaction to pull requests you find important.

[khaneliman]

Relevant bit: https://github.com/Mic92/nixpkgs-review/blob/df034b59d756e80d30532d0756809d4536307098/nixpkgs_review/cli/pr.py#L48-L56

Technically, should still be usable... should just fallback to the old behavior of always evaluating locally. But, is a better experience (much better) with using the results from CI.

[SigmaSquadron]

Also, some users simply cannot run the local evaluation at all, due to memory constraints. Using GitHub Actions' evaluation should lower the barrier of entry for contributors with lower-end machines.

[khaneliman]

Also, some users simply cannot run the local evaluation at all, due to memory constraints. Using GitHub Actions' evaluation should lower the barrier of entry for contributors with lower-end machines.

True, I used to oom my compositor when running with 4 parallel evaluations :P

[JohnRTitor]

Sounds like a good addition to me.

[infinisil]

LGTM!