[FIX] pos_sale: convert string -> datetime.date

fixes #27467

closes odoo/odoo#27468

addons/pos_sale/models/crm_team.py

@@ -91,7 +91,7 @@ class CrmTeam(models.Model):
                 )
                 if self.dashboard_graph_group_pos == 'day':
                     for data_point in order_data:
-                        result.append({'x_value': fields.Date.to_string((fields.datetime.strptime(data_point.get('date:day'), "%d %b %Y"))), 'y_value': data_point.get('price_total')})
+                        result.append({'x_value': fields.Date.to_date(datetime.strptime(data_point.get('date:day'), "%d %b %Y")), 'y_value': data_point.get('price_total')})
                 elif self.dashboard_graph_group_pos == 'week':
                     for data_point in order_data:
                         result.append({'x_value': int(data_point.get('date:week')[1:3]), 'y_value': data_point.get('price_total')})