Update app.py

app.py

@@ -59,8 +59,7 @@ def show_map(lon_from, lat_from, lon_to, lat_to):
         mode = "markers",
         lon = [lon_from, lon_to],
         lat = [lat_from, lat_to],
-        marker = go.scattermapbox.SymbolMarker(
-            symbol='marker',
+        marker = go.scattermapbox.Marker(
             size=25,
             color='red'
         )