Replace depracated --fast nix option

The option is throwing a deprecation warning on current nix versions.
See for details: https://github.com/NixOS/nixpkgs/issues/417609#issuecomment-2981327326

pkgs/clan-cli/clan_lib/machines/update.py

@@ -182,7 +182,8 @@ def run_machine_update(
 
         if machine._class_ == "nixos":
             nix_options += [
-                "--fast",
+                "--no-reexec",
+                "--no-build-nix",
                 "--build-host",
                 "",
             ]