OSIS-91 Change queryset to get an OfferYearCalendar
OSIS-91 Change queryset to get an OfferYearCalendar

uclouvain/OSIS-Louvain,uclouvain/osis_louvain,uclouvain/osis_louvain,uclouvain/OSIS-Louvain,uclouvain/osis_louvain,uclouvain/osis,uclouvain/osis,uclouvain/osis,uclouvain/OSIS-Louvain,uclouvain/osis