remove future (#6065)

superset/models/sql_lab.py

@@ -1,11 +1,6 @@
 # -*- coding: utf-8 -*-
 # pylint: disable=C,R,W
 """A collection of ORM sqlalchemy models for SQL Lab"""
-from __future__ import absolute_import
-from __future__ import division
-from __future__ import print_function
-from __future__ import unicode_literals
-
 from datetime import datetime
 import re