update yarn commands, and add Black formatting
update yarn commands, and add Black formatting

learningequality/kolibri,mrpau/kolibri,mrpau/kolibri,mrpau/kolibri,indirectlylit/kolibri,mrpau/kolibri,indirectlylit/kolibri,lyw07/kolibri,learningequality/kolibri,learningequality/kolibri,lyw07/kolibri,learningequality/kolibri,lyw07/kolibri,lyw07/kolibri,indirectlylit/kolibri,indirectlylit/kolibri