Removed Python 2 string compatibility

netbox/ipam/migrations/0013_prefix_add_is_pool.py

@@ -1,7 +1,5 @@
 # -*- coding: utf-8 -*-
 # Generated by Django 1.10.4 on 2016-12-27 19:34
-from __future__ import unicode_literals
-
 from django.db import migrations, models
 import django.db.models.deletion
 import ipam.fields