python.pkgs.fontforge: disable with Python 2

Since the latest update, fontforge no longer supports building with Python 2. Let's prevent failing builds.

pkgs/top-level/python-packages.nix

@@ -3996,10 +3996,10 @@ in {
 
   folium = callPackage ../development/python-modules/folium { };
 
-  fontforge = toPythonModule (pkgs.fontforge.override {
+  fontforge = disabledIf (!isPy3k) (toPythonModule (pkgs.fontforge.override {
     withPython = true;
     inherit python;
-  });
+  }));
 
   fonttools = callPackage ../development/python-modules/fonttools { };