use latest file on aws s3 bucket python
get_last_modified = lambda obj: int(obj['LastModified'].strftime('%s'))
s3 = boto3.client('s3')
objs = s3.list_objects_v2(Bucket='my_bucket')['Contents']
last_added = [obj['Key'] for obj in sorted(objs, key=get_last_modified)][0]