qnotero: mark broken on Darwin

pkgs/applications/office/qnotero/default.nix

···
-{ lib, fetchFromGitHub, python3Packages, wrapQtAppsHook }:
+{ lib, stdenv, fetchFromGitHub, python3Packages, wrapQtAppsHook }:
 
 python3Packages.buildPythonPackage rec {
   pname = "qnotero";
···
     homepage = "https://www.cogsci.nl/software/qnotero";
     license = lib.licenses.gpl2;
     platforms = lib.platforms.unix;
+    broken = stdenv.isDarwin; # Build fails even after adding cx-freeze to `buildInputs`
     maintainers = [ lib.maintainers.nico202 ];
   };
 }