microfetch: add update script

pkgs/by-name/mi/microfetch/package.nix

@@ -2,6 +2,7 @@
   lib,
   rustPlatform,
   fetchFromGitHub,
+  nix-update-script,
 }:
 
 rustPlatform.buildRustPackage rec {
@@ -17,6 +18,8 @@ rustPlatform.buildRustPackage rec {
 
   cargoHash = "sha256-dGlAiPrOWFI8ogo/1S2ZK/ZPBtKGCyA72B+6B4bp5Mg=";
 
+  passthru.updateScript = nix-update-script { };
+
   meta = {
     description = "Microscopic fetch script in Rust, for NixOS systems";
     homepage = "https://github.com/NotAShelf/microfetch";