I added holidays as part of the regular opening hours: https://www.openstreetmap.org/changeset/158953820

I got anecdotal evidence (the best kind of evidence!) from locals to the neighbourhood that this DQ is regularly open on holidays (but that they don't know the exact hours.) I also remember seeing this DQ open on family day before. Given that it seems commonly known around here that this DQ is open on holidays, and there is no evidence on the building saying it changes its hours on holidays, I think just included holidays as part of normal hours is sensible.