[FIX] Calculate taxes when invoice_id is sliced and has withhold taxes (

#770)

* [FIX] Calculate taxes when invoice_id is sliced and has withhold taxes

* [FIX] Flake8

account_group_invoices/models/account_invoice.py

@@ -116,7 +116,22 @@ def _create_invoices_grouped(self, inv):
             'team_id': team_ids[0].id if team_ids else False
         })
         for line in inv['lines']:
-            line.copy({'invoice_id': gr_invoice_id.id})
+            vals = {
+                'invoice_id': gr_invoice_id.id,
+                'product_id': line.product_id.id,
+                'quantity': line.quantity,
+                'price_unit': line.price_unit,
+                'name': line.name,
+                'sequence': line.sequence,
+                'origin': line.origin,
+                'account_id': line.account_id.id,
+                'invoice_line_tax_ids': [
+                    (6, 0, [tax.id for tax in line.invoice_line_tax_ids])]
+                }
+            new_line = self.env['account.invoice.line'].create(vals)
+            new_line._br_account_onchange_product_id()
+            new_line._set_taxes_from_fiscal_pos()
+        gr_invoice_id._onchange_invoice_line_ids()
 
         cancel_msg = ("""
             <p>This invoice was canceled by group rule named %s and