Add the migration intended to go with r18206. Commit ready for merge.

 - Legacy-Id: 18207

Author: rjsparks

ietf/meeting/migrations/0030_allow_empty_joint_with_sessions.py

@@ -0,0 +1,18 @@
+# Generated by Django 2.2.14 on 2020-07-20 14:11
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('meeting', '0029_businessconstraint'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='session',
+            name='joint_with_groups',
+            field=models.ManyToManyField(blank=True, related_name='sessions_joint_in', to='group.Group'),
+        ),
+    ]