add an node install step in build-images action

.forgejo/workflows/build-images.yaml

@@ -8,13 +8,9 @@ jobs:
     name: Build NixOS images
     runs-on: nixos
     steps:
-      #- name: install sudo
-      #  run: apt-get update && apt-get -y install sudo
+      - name: install node
+        run: nix-env -iA nixos.nodejs_20
       - name: checkout repository
         uses: actions/checkout@v4
-      #- name: install nix
-      #  uses: https://git.distrilab.fr/nix-clic/install-nix-action@v27
-      #  with:
-      #    nix_path: nixpkgs=channel:nixos-24.05
       - name: run generator
         run: nix-shell -p nixos-generators --run "nixos-generate -c inventory/demo-configuration.nix -f proxmox-lxc"