Cleanup migration

misago/cache/migrations/0001_initial.py

@@ -1,8 +1,6 @@
-# -*- coding: utf-8 -*-
 # Generated by Django 1.11.16 on 2018-11-25 15:15
-from __future__ import unicode_literals
-
 from django.db import migrations, models
+
 import misago.cache.utils