migration for ChangedObject.updated_fields to use DjangoJSONEncoder

(does not change db)

src/c3nav/editor/migrations/0003_changedobject_json_encoder.py

@@ -0,0 +1,19 @@
+# Generated by Django 4.2.7 on 2023-12-20 22:25
+
+import django.core.serializers.json
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('editor', '0002_django_4_0'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='changedobject',
+            name='updated_fields',
+            field=models.JSONField(default=dict, encoder=django.core.serializers.json.DjangoJSONEncoder, verbose_name='updated fields'),
+        ),
+    ]