fix: unibox.traverses(s3): allow dir to be shown (with trailing slash)
python
import unibox
artists_root_dir = "s3://dataset-artstation-uw2/artists/"
artists_s3 = unibox.traverses(artists_root_dir)
unibox.peeks(artists_s3, n=5)
returns:
{'metadata': {'len': 646361, 'item_type': 'str'},
'preview': ['artists/-451-/',
'artists/-afei-/',
'artists/-apostart-/',
'artists/-bug-/',
'artists/-cgc-/']}