Update files from the datasets library (from 1.6.0)

Release notes: https://github.com/huggingface/datasets/releases/tag/1.6.0

docred.py

@@ -1,6 +1,5 @@
 """DocRED: A Large-Scale Document-Level Relation Extraction Dataset"""
 
-from __future__ import absolute_import, division, print_function
 
 import json
 import os