nixos/github-runners: add `nodeRuntimes` option

nixos/doc/manual/release-notes/rl-2311.section.md

···
 
 - `services.prometheus.exporters` has a new [exporter](https://github.com/hipages/php-fpm_exporter) to monitor PHP-FPM processes, see [#240394](https://github.com/NixOS/nixpkgs/pull/240394) for more details.
 
+- `services.github-runner` / `services.github-runners.<name>` gained the option `nodeRuntimes`. The option defaults to `[ "node20" ]`, i.e., the service supports Node.js 20 GitHub Actions only. The list of Node.js versions accepted by `nodeRuntimes` tracks the versions the upstream GitHub Actions runner supports. See [#249103](https://github.com/NixOS/nixpkgs/pull/249103) for details.
+
 - `programs.gnupg.agent.pinentryFlavor` is now set in `/etc/gnupg/gpg-agent.conf`, and will no longer take precedence over a `pinentry-program` set in `~/.gnupg/gpg-agent.conf`.
 
 - `wrapHelm` now exposes `passthru.pluginsDir` which can be passed to `helmfile`. For convenience, a top-level package `helmfile-wrapped` has been added, which inherits `passthru.pluginsDir` from `kubernetes-helm-wrapped`. See [#217768](https://github.com/NixOS/nixpkgs/issues/217768) for details.

nixos/modules/services/continuous-integration/github-runner/options.nix

···
     '';
     default = null;
   };
+
+  nodeRuntimes = mkOption {
+    type = with types; nonEmptyListOf (enum [ "node16" "node20" ]);
+    default = [ "node20" ];
+    description = mdDoc ''
+      List of Node.js runtimes the runner should support.
+    '';
+  };
 }

nixos/modules/services/continuous-integration/github-runner/service.nix

···
 
 let
   workDir = if cfg.workDir == null then runtimeDir else cfg.workDir;
+  package = cfg.package.override { inherit (cfg) nodeRuntimes; };
 in
 {
   description = "GitHub Actions runner";
···
 
   serviceConfig = mkMerge [
     {
-      ExecStart = "${cfg.package}/bin/Runner.Listener run --startuptype service";
+      ExecStart = "${package}/bin/Runner.Listener run --startuptype service";
 
       # Does the following, sequentially:
       # - If the module configuration or the token has changed, purge the state directory,
···
               else
                 args+=(--token "$token")
               fi
-              ${cfg.package}/bin/Runner.Listener configure "''${args[@]}"
+              ${package}/bin/Runner.Listener configure "''${args[@]}"
               # Move the automatically created _diag dir to the logs dir
               mkdir -p  "$STATE_DIRECTORY/_diag"
               cp    -r  "$STATE_DIRECTORY/_diag/." "$LOGS_DIRECTORY/"