Update imports for Python 3.4+

modoboa/dnstools/factories.py

@@ -1,7 +1,5 @@
 """App related factories."""
 
-from __future__ import unicode_literals
-
 import factory
 
 from modoboa.admin import factories as admin_factories

modoboa/dnstools/lib.py

@@ -1,7 +1,5 @@
 """dnstools library."""
 
-from __future__ import unicode_literals
-
 import ipaddress
 
 from django.utils.translation import ugettext as _

modoboa/dnstools/migrations/0001_initial.py

@@ -1,7 +1,5 @@
 # -*- coding: utf-8 -*-
 # Generated by Django 1.11.16 on 2018-11-19 10:07
-from __future__ import unicode_literals
-
 from django.db import migrations, models
 import django.db.models.deletion
 import django.utils.timezone

modoboa/dnstools/models.py

@@ -1,7 +1,5 @@
 """App related models."""
 
-from __future__ import unicode_literals
-
 import datetime
 
 from django.db import models