resolve migration conflict

#52 bump 0.7.7 to 0.7.8 and release on PyPI

Author: codekiln

django_elastic_migrations/migrations/0007_auto_20181111_1251.py

@@ -1,8 +1,7 @@
-# -*- coding: utf-8 -*-
-# Generated by Django 1.11 on 2018-11-12 09:37
-from __future__ import unicode_literals
+# Generated by Django 2.1.3 on 2018-11-13 09:58
 
 from django.db import migrations, models
+import django.db.models.deletion
 
 
 class Migration(migrations.Migration):
@@ -15,6 +14,11 @@ class Migration(migrations.Migration):
         migrations.DeleteModel(
             name='DeactivateIndexAction',
         ),
+        migrations.AlterField(
+            model_name='index',
+            name='active_version',
+            field=models.ForeignKey(null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='+', to='django_elastic_migrations.IndexVersion'),
+        ),
         migrations.AlterField(
             model_name='indexaction',
             name='action',