diff-so-fancy: add updateScript

pkgs/by-name/di/diff-so-fancy/package.nix

@@ -7,6 +7,7 @@
   coreutils,
   fetchFromGitHub,
   makeWrapper,
+  nix-update-script,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
@@ -52,6 +53,8 @@ stdenv.mkDerivation (finalAttrs: {
     runHook postInstall
   '';
 
+  passthru.updateScript = nix-update-script { };
+
   meta = {
     homepage = "https://github.com/so-fancy/diff-so-fancy";
     description = "Good-looking diffs filter for git";