Deref team captain username

insalan/tournament/views/tournament.py

@@ -117,6 +117,7 @@ def get(self, request, primary_key: int):
                         "payment_status": Substitute.objects.get(id=pid).payment_status if can_see_payment_status else None
                     } for pid in team_preser["substitutes"]
                 ]
+                team_preser["captain"] = Player.objects.get(id=team_preser["captain"]).as_user().username if team_preser["captain"] is not None else None
                 teams_serialized.append(team_preser)
             # deref groups
             group_serialized = []