nixos/github-runner: use bashInteractive instead of bash (#339875)

Some github actions that use `bash` expect interactive features to be available. One such action is the [use-nix-shell](https://github.com/rrbutani/use-nix-shell-action) action. I couldn't find a way to override this even with `cfg.extraPackages`, due to the way the path is ordered.

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

@@ -52,7 +52,7 @@ with lib;
       } // cfg.extraEnvironment;
 
       path = (with pkgs; [
-        bash
+        bashInteractive
         coreutils
         git
         gnutar