@api.depends('date_from')

    def _compute_month(self):

        for rec in self:

            date_from = datetime.strptime(rec.date_from, "%Y-%m-%d").date()

    rec.month = date_from.month

            rec.year = date_from.year

Solution: Try to change the following line as below:
                date_from = datetime.strptime(str(rec.date_from), "%Y-%m-%d").date()

Note: Remember one thing, when we use:  from datetime import datetime
            then use this: date_from = datetime.strptime(str(rec.date_from), "%Y-%m-%d").date()
            But when we use only: import datetime
            Then use:  date_from = datetime.datetime.strptime(str(rec.date_from), "%Y-%m-%d").date()

Hope it will help. Thanks.