Fix GeoPandas dataset compatibility for naturalearth_cities

[AliAbouelazm]

Update documentation examples to support both GeoPandas < 1.0 and >= 1.0.

Context: GeoPandas 1.0 removed the datasets accessor used in gpd.datasets.get_path("naturalearth_cities").

Changes:

• Try old method first for backward compatibility
• Fallback to geodatasets package for GeoPandas >= 1.0
• Final fallback to a public GeoJSON URL if geodatasets is not available

Files updated:

• doc/python/scatter-plots-on-maps.md
• doc/python/tile-scatter-maps.md

Docs-only change.

[camdecoster]

Thanks for the PR! We'll try to review this as we have time. This seems to be related to #4782.

[LiamConnors]

Thanks for the PR! I have added a few comments. Let me know if you have any questions.

[LiamConnors]

This dataset doesn't currently exist on geodatasets, so this will never be successful even with geopandas >=1.0

[LiamConnors]

As 'naturalearth.cities' does not exist on geodatasets, I think the best thing to do here would be to have just the example of the dataframe created using GeoDataFrame, like you show in the except block, but with some real cities.

So something like

import plotly.express as px
import geopandas as gpd
from shapely.geometry import Point

geo_df = gpd.GeoDataFrame({
    'name': ['London', 'Paris', 'Berlin', 'Madrid', 'Rome'],
    'geometry': [
        Point(-0.13, 51.51),
        Point(2.35, 48.86),
        Point(13.41, 52.52),
        Point(-3.70, 40.42),
        Point(12.50, 41.90),
    ]
}, crs="EPSG:4326")

fig = px.scatter_map(geo_df,
                    lat=geo_df.geometry.y,
                    lon=geo_df.geometry.x,
                    hover_name="name",
                    zoom=3)
fig.show()

And something similar for the scatter-plots-on-maps example