caprine: add updateScript

easier to call update command for me

pkgs/by-name/ca/caprine/package.nix

@@ -6,6 +6,7 @@
   makeDesktopItem,
   copyDesktopItems,
   electron,
+  nix-update-script,
 }:
 
 buildNpmPackage rec {
@@ -79,6 +80,8 @@ buildNpmPackage rec {
     })
   ];
 
+  passthru.updateScript = nix-update-script { };
+
   meta = {
     changelog = "https://github.com/sindresorhus/caprine/releases/tag/${src.rev}";
     description = "Elegant Facebook Messenger desktop app";