Support identity API v3 when generate clouds.yaml

When using IDENTITY_API_VERSION=3, the clouds.yaml must also set
auth/user_domain_id and project_domain_id.

Change-Id: If028f2935ea729276f40039a4003c07c08e91672
diff --git a/tools/update_clouds_yaml.py b/tools/update_clouds_yaml.py
index 0862135..3a364fe 100755
--- a/tools/update_clouds_yaml.py
+++ b/tools/update_clouds_yaml.py
@@ -43,6 +43,9 @@
                 'project_name': args.os_project_name,
             },
         }
+        if args.os_identity_api_version == '3':
+            self._cloud_data['auth']['user_domain_id'] = 'default'
+            self._cloud_data['auth']['project_domain_id'] = 'default'
         if args.os_cacert:
             self._cloud_data['cacert'] = args.os_cacert