python-jupyter-packaging: update to 0.12.3
python-jupyter-packaging: update to 0.12.3

lhmouse/MINGW-packages,oscarfv/MINGW-packages,oscarfv/MINGW-packages,stahta01/MINGW-packages,lhmouse/MINGW-packages,JPeterMugaas/MINGW-packages,JPeterMugaas/MINGW-packages,JPeterMugaas/MINGW-packages,lhmouse/MINGW-packages,oscarfv/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,lhmouse/MINGW-packages,oscarfv/MINGW-packages,JPeterMugaas/MINGW-packages,JPeterMugaas/MINGW-packages,JPeterMugaas/MINGW-packages,stahta01/MINGW-packages,stahta01/MINGW-packages,stahta01/MINGW-packages,lhmouse/MINGW-packages,stahta01/MINGW-packages,oscarfv/MINGW-packages,oscarfv/MINGW-packages