`update_redcap_record` does not update fields when the value was NULL

[psadil]

update_redcap_record compares and old record object with a new one, attempting to update any fields that have changed, and then passing the updated object to the vbr_client.update_row for updating the database:

python-vbr/src/vbr/api/redcap.py

Lines 48 to 57 in 6641b13

	def update_redcap_record(
	self, redcap_form_name: str, redcap_record: RcapTable, rcap_row: RcapTable
	) -> RcapTable:
	"""Update RedCap row based on RedCap API response"""
	for k,v in redcap_record.dict().items():
	old_value = rcap_row.dict().get(k,None)
	if old_value is not None and old_value != v:
	setattr(rcap_row,k,v)
	rcap_row = self.vbr_client.update_row(rcap_row)
	return rcap_row

But the comparison of old vs new values prevents updating when the old values were None (e.g., can't fill a previously NULL value)

            if old_value is not None and old_value != v:

I think this should be something like

       if (
            (old_value is None and v is not None)
            or (old_value is not None and v is None)
            or (old_value != v)
        ):