Fix migrations (replace JSON field etc.)

aleksis/apps/alsijil/migrations/0001_initial.py

 # Generated by Django 3.0.6 on 2020-05-29 10:29
 
-import django.contrib.postgres.fields.jsonb
 import django.contrib.sites.managers
 import django.db.models.deletion
 from django.db import migrations, models
@@ -33,7 +32,7 @@ class Migration(migrations.Migration):
                 ),
                 (
                     "extended_data",
-                    django.contrib.postgres.fields.jsonb.JSONField(
+                    models.JSONField(
                         default=dict, editable=False
                     ),
                 ),
@@ -92,7 +91,7 @@ class Migration(migrations.Migration):
                 ),
                 (
                     "extended_data",
-                    django.contrib.postgres.fields.jsonb.JSONField(
+                    models.JSONField(
                         default=dict, editable=False
                     ),
                 ),
@@ -140,7 +139,7 @@ class Migration(migrations.Migration):
                 ],
                 "unique_together": {("lesson_period", "week", "person")},
             },
-            managers=[("objects", django.contrib.sites.managers.CurrentSiteManager()),],
+            managers=[],
         ),
         migrations.CreateModel(
             name="LessonDocumentation",
@@ -156,7 +155,7 @@ class Migration(migrations.Migration):
                 ),
                 (
                     "extended_data",
-                    django.contrib.postgres.fields.jsonb.JSONField(
+                    models.JSONField(
                         default=dict, editable=False
                     ),
                 ),
@@ -202,6 +201,6 @@ class Migration(migrations.Migration):
                 ],
                 "unique_together": {("lesson_period", "week")},
             },
-            managers=[("objects", django.contrib.sites.managers.CurrentSiteManager()),],
+            managers=[],
         ),
     ]