Fix compatibility with gabbi >= 2.7.0

Fix the argument error caused by the change[1] in gabbi 2.7.0 .

[1] https://github.com/cdent/gabbi/commit/8511156559651ab0bf9d2679816d5a7818af290b

Change-Id: I936a3e6ddb0c254069839aaaa1f0eb7d4a72c85d
diff --git a/telemetry_tempest_plugin/scenario/utils.py b/telemetry_tempest_plugin/scenario/utils.py
index 0904160..9be8fe1 100644
--- a/telemetry_tempest_plugin/scenario/utils.py
+++ b/telemetry_tempest_plugin/scenario/utils.py
@@ -38,7 +38,7 @@
         host='example.com', port=None,
         fixture_module=None,
         intercept=None,
-        handlers=runner.initialize_handlers([]),
+        handlers=runner.initialize_handlers([], []),
         test_loader_name="tempest")
 
     # NOTE(sileht): We hide stdout/stderr and reraise the failure