Lock dandiset when changing owner list

[waxlamp]

Originally posted by @mvandenburgh in #1886 (comment):

This problem existed before this PR, but I'll just mention that by the time this .save() is called this Dandiset object might be stale. I think we need to lock the dandiset object with select_for_update.

dandi-archive/dandiapi/api/views/dandiset.py

Lines 416 to 420 in 0a225f4

	# All owners found
	with transaction.atomic():
	owners = user_owners + [acc.user for acc in socialaccount_owners]
	removed_owners, added_owners = dandiset.set_owners(owners)
	dandiset.save()

[dandibot]

🚀 Issue was released in v0.5.0 🚀