fix: add noop django 4 migration (#134)

* fix: add noop django 4 migration

* fix: isort

djangocms_snippet/migrations/0009_alter_snippetptr_cmsplugin_ptr.py

@@ -0,0 +1,20 @@
+# Generated by Django 4.1.7 on 2023-02-28 16:57
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('cms', '0022_auto_20180620_1551'),
+        ('djangocms_snippet', '0008_auto_change_name'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='snippetptr',
+            name='cmsplugin_ptr',
+            field=models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, related_name='%(app_label)s_%(class)s', serialize=False, to='cms.cmsplugin'),
+        ),
+    ]