pantheon.elementary-notifications: add updateScript

pkgs/desktops/pantheon/services/elementary-notifications/default.nix

@@ -1,6 +1,7 @@
 { lib
 , stdenv
 , fetchFromGitHub
+, nix-update-script
 , meson
 , ninja
 , pkg-config
@@ -50,6 +51,12 @@ stdenv.mkDerivation rec {
     patchShebangs meson/post_install.py
   '';
 
+  passthru = {
+    updateScript = nix-update-script {
+      attrPath = "pantheon.${pname}";
+    };
+  };
+
   meta = with lib; {
     description = "GTK notification server for Pantheon";
     homepage = "https://github.com/elementary/notifications";