Refs #27996 -- Doc'd no extension required for RandomUUID() on PostgreSQL 13+.

https://www.postgresql.org/docs/13/functions-uuid.html
https://www.postgresql.org/docs/13/pgcrypto.html#id-1.11.7.34.10.5

tests/postgres_tests/migrations/0001_setup_extensions.py

@@ -1,6 +1,6 @@
 from unittest import mock
 
-from django.db import migrations
+from django.db import connection, migrations
 
 try:
     from django.contrib.postgres.operations import (
@@ -14,10 +14,12 @@ except ImportError:
     BtreeGistExtension = mock.Mock()
     CITextExtension = mock.Mock()
     CreateExtension = mock.Mock()
-    CryptoExtension = mock.Mock()
     HStoreExtension = mock.Mock()
     TrigramExtension = mock.Mock()
     UnaccentExtension = mock.Mock()
+    needs_crypto_extension = False
+else:
+    needs_crypto_extension = not connection.features.is_postgresql_13
 
 
 class Migration(migrations.Migration):
@@ -30,7 +32,8 @@ class Migration(migrations.Migration):
         # Ensure CreateExtension quotes extension names by creating one with a
         # dash in its name.
         CreateExtension('uuid-ossp'),
-        CryptoExtension(),
+        # CryptoExtension is required for RandomUUID() on PostgreSQL < 13.
+        CryptoExtension() if needs_crypto_extension else mock.Mock(),
         HStoreExtension(),
         TrigramExtension(),
         UnaccentExtension(),