#15 fix incorrect decoding to csv

[Tsovak]

resolves #15

input data from issie #15 has a h3 that actually is a big string array

with zipcode_geom as (
    SELECT
        ST_GEOGFROMTEXT(zipcode_geom) as geom,
        bqcarto.h3.ST_ASH3_POLYFILL(ST_GEOGFROMTEXT(zipcode_geom), 10) as h3,
        zipcode
    FROM `bigquery-public-data.utility_us.zipcode_area`
    WHERE city = 'Seattle city' and zipcode='98105'
)

select
 ARRAY_LENGTH(h3),
 *
FROM zipcode_geom

BQ decoder returns decoded data like map[string]interface{} in most cases, but in the current case, it returns as a string array for the h3 column. in line of 65 we return an error when couldn't cast to map, instead of that I added a type checker that added to the column any data like an array or just an interface.
Added the pic to make to more clear

Btw, in Google chrome, the column is seen, but in Safari isn't. I think it should be another issue
proofs

[delfrrr]

Indeed, I was able to reproduce, thank you for the fix!