Improve typing of the metadata parameter#1490

JeanChristopheMorinPerso wants to merge 21 commits into

AcademySoftwareFoundation:mainAcademySoftwareFoundation/OpenTimelineIO:mainfrom

JeanChristopheMorinPerso:metadata_better_typeJeanChristopheMorinPerso/OpenTimelineIO:metadata_better_typeCopy head branch name to clipboard