Removing unneeded from __future__ import statements.

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

ebook_converter/tinycss/color3.py

@@ -1,4 +1,3 @@
-# coding: utf8
 """
     tinycss.colors3
     ---------------
@@ -12,8 +11,6 @@
     :copyright: (c) 2012 by Simon Sapin.
     :license: BSD, see LICENSE for more details.
 """
-
-from __future__ import unicode_literals, division
 import collections
 import itertools
 import re