inconsistent behaviour with date_object_value class

[TarekSalha]

Describe the bug
in the setter for the value property, it is not possible to insert a date object, but only str or datetime's:

@value.setter
    def value(self, value):
        if isinstance(value, **datetime**):
            self._value = value
        else:
            if isinstance(value, six.string_types):
                value = parse(value).date()
                self._value = value

this is inconsistent with the API behaviour, that will return me with get_sheet() a date object inside the object_value property of a cell. but then, I am not able to write a date object, but need to isoformat it as string before sending it back to smartsheet with update_rows().

Expected behavior
the setter should be accepting date type as well to make it more convenient to use the object_value field.

Environment (please complete the following information):

• OS: Windows 10
• Smartsheet Python SDK Version: 3.0.2
• Python Version: 3.9