remove default zoom of 8

Author: emilykl

plotly/express/_chart_types.py

@@ -1276,7 +1276,7 @@ def scatter_map(
     color_continuous_midpoint=None,
     opacity=None,
     size_max=None,
-    zoom=8,
+    zoom=None,
     center=None,
     map_style=None,
     title=None,
@@ -1314,7 +1314,7 @@ def choropleth_map(
     range_color=None,
     color_continuous_midpoint=None,
     opacity=None,
-    zoom=8,
+    zoom=None,
     center=None,
     map_style=None,
     title=None,