don't show scheckbuch-people in stat

src/model/stat.rs

@@ -27,6 +27,7 @@ INNER JOIN (
     FROM logbook l
     WHERE l.distance_in_km IS NOT NULL
 ) sub ON u.id = sub.user_id
+WHERE u.is_guest = false
 GROUP BY u.name
 ORDER BY rowed_km DESC;
 ",