ckan: add passthru.updateScript

pkgs/by-name/ck/ckan/package.nix

@@ -9,6 +9,7 @@
   imagemagick,
   copyDesktopItems,
   makeDesktopItem,
+  nix-update-script,
 }:
 
 stdenv.mkDerivation rec {
@@ -75,6 +76,8 @@ stdenv.mkDerivation rec {
     })
   ];
 
+  passthru.updateScript = nix-update-script { };
+
   meta = with lib; {
     description = "Mod manager for Kerbal Space Program";
     mainProgram = "ckan";