Update example osm_invest

osmnx renamed geometries_from_polygon to features_from_polygon and
removed the column "node".

examples/optimisation/import_osm_invest/import_osm_invest.py

@@ -70,17 +70,13 @@
 graph = ox.graph_from_polygon(polygon, network_type='drive_service')
 ox.plot_graph(graph)
 
-gdf_poly_houses = ox.geometries_from_polygon(polygon, tags=buildings)
-gdf_lines_streets = ox.geometries_from_polygon(polygon, tags=streets)
+gdf_poly_houses = ox.features_from_polygon(polygon, tags=buildings)
+gdf_lines_streets = ox.features_from_polygon(polygon, tags=streets)
 
 # Make sure that only polygon geometries are used
 gdf_poly_houses = gdf_poly_houses[gdf_poly_houses['geometry'].apply(
     lambda x: isinstance(x, geometry.Polygon))]
 
-# Remove nodes column (that make somehow trouble for exporting .geojson)
-gdf_poly_houses.drop(columns=['nodes'], inplace=True)
-gdf_lines_streets.drop(columns=['nodes'], inplace=True)
-
 # We need one (or more) buildings that we call "generators".
 # Choose one among the buildings at random and move it to a new GeoDataFrame
 np.random.seed(42)