add max height to the city in geojson when the high field is given

hub/imports/geometry/geojson.py

@@ -116,6 +116,7 @@ class Geojson:
         if self._extrusion_height_field is not None:
           extrusion_height = float(feature['properties'][self._extrusion_height_field])
           lod = 1
+          self._max_z = max(self._max_z, extrusion_height)
         year_of_construction = None
         if self._year_of_construction_field is not None:
           year_of_construction = int(feature['properties'][self._year_of_construction_field])