polyfill fails with valid multipolygon geojson

[kangeugine]

h3_pyspark.polyfill fails when a valid multipolygon geojson is provided
this is expected behavior when utilizing the h3 native library.

however, i thought it would be helpful if this library is able to accept multipolygons.
could I get permission to push a PR?

implementation in src/h3_pyspark/__init__.py

@F.udf(returnType=T.ArrayType(T.StringType()))
@handle_nulls
def polyfill(polygons, res, geo_json_conformant):
    # NOTE: this behavior differs from default
    # h3-pyspark expect `polygons` argument to be a valid GeoJSON string
    polygons = json.loads(polygons)
    type_ = polygons["type"].lower()
    if type_ == "multipolygon":
        output = []
        for i in polygons["coordinates"]:
            _polygon = {"type": "Polygon", "coordinates": i}
            output.extend(list(h3.polyfill(_polygon, res, geo_json_conformant)))
        return sanitize_types(output)
    return sanitize_types(h3.polyfill(polygons, res, geo_json_conformant))

test in tests/test_core.py

multipolygon = '{"type": "MultiPolygon","coordinates": [[[[108.98309290409088,13.240363245242063],[108.98343622684479,13.240363245242063],[108.98343622684479,13.240634779729014],[108.98309290409088,13.240634779729014],[108.98309290409088,13.240363245242063]]],[[[108.98349523544312,13.240002939397714],[108.98389220237732,13.240002939397714],[108.98389220237732,13.240269252464502],[108.98349523544312,13.240269252464502],[108.98349523544312,13.240002939397714]]]]}'

def test_polyfill_multipolygon(self):
        h3_test_args, h3_pyspark_test_args = get_test_args(h3.polyfill)
        print(h3_pyspark_test_args)
        integer = 12
        data = {
            "res": integer,
            "geo_json_conformant": True,
            "geojson": multipolygon,
        }
        df = spark.createDataFrame([data])
        actual = df.withColumn("actual", h3_pyspark.polyfill(*h3_pyspark_test_args))
        actual = actual.collect()[0]["actual"]
        print(actual)
        expected = []
        for i in json.loads(multipolygon)["coordinates"]:
            _polygon = {"type": "Polygon", "coordinates": i}
            expected.extend(list(h3.polyfill(_polygon, integer, True)))
        expected = sanitize_types(expected)
        assert sort(actual) == sort(expected)