Changed input type of event date config from datetime back to string.
Changed input type of event date config from datetime back to string.

FinnStutzenstein/OpenSlides,ostcar/OpenSlides,CatoTH/OpenSlides,ostcar/OpenSlides,normanjaeckel/OpenSlides,CatoTH/OpenSlides,jwinzer/OpenSlides,OpenSlides/OpenSlides,CatoTH/OpenSlides,FinnStutzenstein/OpenSlides,normanjaeckel/OpenSlides,OpenSlides/OpenSlides,ostcar/OpenSlides,tsiegleauq/OpenSlides,jwinzer/OpenSlides,normanjaeckel/OpenSlides,jwinzer/OpenSlides,jwinzer/OpenSlides,FinnStutzenstein/OpenSlides,jwinzer/OpenSlides,FinnStutzenstein/OpenSlides,tsiegleauq/OpenSlides,CatoTH/OpenSlides,tsiegleauq/OpenSlides,normanjaeckel/OpenSlides