Save the link to the created invoice when processing Peppol invoice

Closes #14444

modules/edocument_peppol/edocument.py

@@ -226,6 +226,7 @@ class Peppol(Workflow, ModelSQL, ModelView):
                 if self.invoice:
                     return
                 self.invoice = Invoice.parse(self.data)
+                self.save()
                 self.succeed()
 
     @classmethod