Add migration for adding range_merge aggregation

Author: jacklinke

django_range_merge/migrations/0001_initial.py

@@ -0,0 +1,17 @@
+# Generated by Django 4.1.2 on 2022-10-09 05:30
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+    
+    dependencies = []
+
+    operations = [
+        migrations.RunSQL(
+            sql=[("CREATE OR REPLACE AGGREGATE range_merge(anyrange)(sfunc=range_merge, stype=anyrange);")],
+            reverse_sql=[("DROP AGGREGATE IF EXISTS range_merge(anyrange);")],
+        )
+    ]