kodiPackages.six: set PYTHON_PATH (#385153)

pkgs/applications/video/kodi/addons/six/default.nix

···
     sha256 = "sha256-d6BNpnTg6K7NPX3uWp5X0rog33C+B7YoAtLH/CrUYno=";
   };
 
-  passthru.updateScript = addonUpdateScript {
-    attrPath = "kodi.packages.six";
+  passthru = {
+    pythonPath = "lib";
+    updateScript = addonUpdateScript {
+      attrPath = "kodi.packages.six";
+    };
   };
 
   meta = with lib; {