Removing unneeded from __future__ import statements.

Since we are on Python 3.6 and up, we don't need those anymore.

ebook_converter/polyglot/urllib.py

@@ -1,11 +1,6 @@
-#!/usr/bin/env python2
-# vim:fileencoding=utf-8
-# License: GPL v3 Copyright: 2018, Kovid Goyal <kovid at kovidgoyal.net>
-
-from __future__ import absolute_import
-
 from ebook_converter.polyglot.builtins import is_py3
 
+
 if is_py3:
     from urllib.request import (build_opener, getproxies, install_opener,  # noqa
             HTTPBasicAuthHandler, HTTPCookieProcessor, HTTPDigestAuthHandler,  # noqa