bug: Dates fail validation because theyre in timestamps format '2021-03-19T00:00:00+00:00' is not a 'date'

[pnadolny13]

The snowflake table definition shows that the columns are date types but when the tap extracts them it returns a string in the format of a timestamp '2021-03-19T00:00:00+00:00' so target validation fails. The json schema for the record looks to be correct {'format': 'date', 'type': ['string', 'null']}.

[nidhi-akkio]

#34