kdlfmt: add updateScript

pkgs/by-name/kd/kdlfmt/package.nix

@@ -5,6 +5,7 @@
   stdenv,
   installShellFiles,
   versionCheckHook,
+  nix-update-script,
 }:
 
 rustPlatform.buildRustPackage (finalAttrs: {
@@ -34,6 +35,8 @@ rustPlatform.buildRustPackage (finalAttrs: {
   versionCheckProgramArg = "--version";
   doInstallCheck = true;
 
+  passthru.updateScript = nix-update-script { };
+
   meta = {
     description = "Formatter for kdl documents";
     homepage = "https://github.com/hougesen/kdlfmt";