nixops: sync nix channel

nixops/desktop.nix

@@ -6,6 +6,7 @@ let
 in
 {
   deployment.targetHost = host;
+  nix.nixPath = [ "nixpkgs=${pkgs.path}" ];
 
   imports =
     [

nixops/light.nix

@@ -3,6 +3,7 @@
 { config, pkgs, ... }:
 {
   deployment.targetHost = host;
+  nix.nixPath = [ "nixpkgs=${pkgs.path}" ];
 
   imports =
     [

nixops/rpi.nix

@@ -6,6 +6,7 @@ let
 in
 {
   deployment.targetHost = host;
+  nix.nixPath = [ "nixpkgs=${pkgs.path}" ];
   nixpkgs.system = "aarch64-linux";
 
   boot.loader.grub.enable = false;