type object ‘datetime.datetime’ has no attribute ‘fromisoformat’

The issue here is actually that fromisoformat is not available in Python versions older than 3.7, you can see that clearly stated in the documenation here.

Return a date corresponding to a date_string given in the format YYYY-MM-DD:
>>>

>>> from datetime import date
>>> date.fromisoformat('2019-12-04')
datetime.date(2019, 12, 4)

This is the inverse of date.isoformat(). It only supports the format YYYY-MM-DD.

New in version 3.7.