umu-launcher-unwrapped: add update script

pkgs/by-name/um/umu-launcher-unwrapped/package.nix

@@ -4,6 +4,7 @@
   fetchFromGitHub,
   hatch,
   lib,
+  nix-update-script,
   python3Packages,
   rustPlatform,
   scdoc,
@@ -83,6 +84,8 @@ python3Packages.buildPythonPackage rec {
     "test_parse_args_noopts"
   ];
 
+  passthru.updateScript = nix-update-script { };
+
   meta = {
     description = "Unified launcher for Windows games on Linux using the Steam Linux Runtime and Tools";
     changelog = "https://github.com/Open-Wine-Components/umu-launcher/releases/tag/${version}";