arfile.py: remove dependency on python-future

Python-future provides a python2 compatible object class (provides next
method). Since method is not used, remove dependency.

Signed-off-by: Alejandro del Castillo <alejandro.delcastillo@ni.com>

arfile.py

@@ -7,7 +7,6 @@ of GNU General Public License v2 or later.
 """
 from __future__ import absolute_import
 from __future__ import print_function
-from builtins import object
 import sys
 import os
 import tarfile