Add hook to allow using GLib

The environment variable `GI_TYPELIB_PATH` needs to be set, otherwise
the kiosk crashes with:

    cannot import name GLib, introspection typelib not found

This is taken care of by `wrapGAppsHook`.

kiosk/default.nix

@@ -17,7 +17,7 @@ python3Packages.buildPythonApplication rec {
 
   doCheck = false;
 
-  nativeBuildInputs = [ qt5.wrapQtAppsHook mypy ];
+  nativeBuildInputs = [ qt5.wrapQtAppsHook mypy wrapGAppsHook ];
 
   propagatedBuildInputs = with python3Packages; [
     dbus-python