Fix generate_custom_slots.py.
Fix generate_custom_slots.py.

Was still calling kodi.SetupEnvVars(), which was dropped in favor of
just calling populate_env() from yaep.

ta264/kodi-alexa,digiltd/kodi-alexa,ausweider/kodi-alexa,jingai/kodi-alexa,m0ngr31/kodi-alexa