remove future (#6065)

superset/sql_parse.py

@@ -1,10 +1,5 @@
 # -*- coding: utf-8 -*-
 # pylint: disable=C,R,W
-from __future__ import absolute_import
-from __future__ import division
-from __future__ import print_function
-from __future__ import unicode_literals
-
 import logging
 
 import sqlparse