workflows: check NixOS/Nixpkgs manual builds for PRs to stable

[lilyinstarlight]

Description of changes

Right now PRs to stable (backport or otherwise) do not build the manuals and so it is possible such a backport could break the manual builds when they change between stable/unstable

This updates the GHA workflow definition to also build the manual on PRs to release-*. I tested it on my nixpkgs fork and the workflow did correctly run

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• 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/)
• 23.05 Release Notes (or backporting 22.11 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.

[zowoq]

It's intentionally disabled for release branches.

As a github action can't start another github action the automated backport PR won't start a build of the nixos manual.

I realise it would have helped in your case as it was a manual backport but it doesn't help for the majority of PRs.

[winterqt]

Does it actively hinder any of the automated backports? If not, I'd say let's just go for it; the more mistakes we can catch the better IMO.

[zowoq]

People see it on their manual backport PRs and expect the same thing on the automated PRs.

A better solution is move both of the manual builds (nixpkgs/nixos) to ofborg.

[lilyinstarlight]

A better solution is move both of the manual builds (nixpkgs/nixos) to ofborg.

Can you say that here then, where it was decided to leave the functionality as GitHub Actions rather than implementing in OfBorg? NixOS/ofborg#609

As a github action can't start another github action the automated backport PR won't start a build of the nixos manual.

Side note, but this is obviously solvable since you can dispatch a workflow with a PR number parameter against the PR commit from the backport workflow (to get the manual workflows to show up and run the same on automated PRs), but I understand that doing this in OfBorg is less hacky and just the better solution

[lilyinstarlight]

People see it on their manual backport PRs and expect the same thing on the automated PRs.

(As another side note, but I expected it for all non-automated PRs so it is surprising behavior regardless of whether or not it happens for automated PRs)

[lilyinstarlight]

Closing in favor of NixOS/ofborg#609