pinwheel/manatee/backwards: Adjust for updated nixpkgs

config-manager/default.nix

@@ -9,7 +9,7 @@ let
   flakePath = config.config-manager.flakePath;
   nixosConfiguration = config.config-manager.nixosConfiguration;
 
-  nh = inputs.nh.packages."${pkgs.system}".default;
+  nh = inputs.nh.packages."${pkgs.stdenv.hostPlatform.system}".default;
 
   config-manager =
     if flakePath == "" then