NotionDate to datetime.datetime

Hello There! I'm trying to export my Notion data to Google Calendar, so, to create my `.ics` file I need to convert `notion.collection.NotionDate` object to `datetime.datetime` object. I've tried to use `row.date._format_datetime(datetime)` but, unfortunately, it didn't work. Help me, please, how to convert NotionDate to datetime.

Start at the row.date object and inspect NotionDate._format_datetime, since these are the only entry points mentioned. Determine the supported way to obtain a datetime.datetime value and document the conversion path or usage; done means a newcomer can use it to create an .ics file.

Written by the indexing model from the issue text.