Support python 3.7 and up

setup.cfg

@@ -30,7 +30,7 @@ classifiers =
 [options]
 zip_safe = False
 include_package_data = True
-python_requires = >= 3.6
+python_requires = >= 3.7
 packages = find:
 package_dir =
     =src

src/port_for/__init__.py

@@ -1,6 +1,4 @@
 # -*- coding: utf-8 -*-
-from __future__ import absolute_import
-
 __version__ = "0.5.0"
 
 from ._ranges import UNASSIGNED_RANGES

src/port_for/api.py

@@ -1,5 +1,4 @@
 # -*- coding: utf-8 -*-
-from __future__ import absolute_import, division, with_statement
 import contextlib
 import socket
 import errno

src/port_for/ephemeral.py

@@ -6,7 +6,6 @@
 
 Currently only Linux and BSD (including OS X) are supported.
 """
-from __future__ import absolute_import, with_statement
 import subprocess
 from typing import List, Tuple, Dict
 

src/port_for/store.py

@@ -1,5 +1,4 @@
 # -*- coding: utf-8 -*-
-from __future__ import absolute_import, with_statement
 import os
 from configparser import ConfigParser, DEFAULTSECT
 from typing import Optional, List, Tuple, Union

src/port_for/utils.py

@@ -1,5 +1,4 @@
 # -*- coding: utf-8 -*-
-from __future__ import absolute_import
 import itertools
 from typing import Iterable, Iterator, Tuple, Set
 

tests/test_cases.py

@@ -1,5 +1,4 @@
 # -*- coding: utf-8 -*-
-from __future__ import absolute_import
 import unittest
 import tempfile
 import mock