Update us-census example to use storage_options

[TomAugspurger]

geopandas/geopandas#2107 added storage options to geopandas' read_parquet. Once it's released, we should update the census notebook to replace

protocol, url = signed_asset.href.split("://")
fs = fsspec.filesystem(protocol, **signed_asset.extra_fields["table:storage_options"])
df = geopandas.read_parquet(url, filesystem=fs)

with

df = geopandas.read_parquet(url, storage_options=signed_asset.extra_fields["table:storage_options"])