test: Fix warning about broker_connection_retry

tests/frameworks/test_celery.py::test_error_reporting
  /usr/local/lib/python3.9/site-packages/celery/worker/consumer/consumer.py:507: CPendingDeprecationWarning: The broker_connection_retry configuration setting will no longer determine
  whether broker connection retries are made during startup in Celery 6.0 and above.
  If you wish to retain the existing behavior for retrying connections on startup,
  you should set broker_connection_retry_on_startup to True.
    warnings.warn(

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html

Signed-off-by: Ferenc Géczi <ferenc.geczi@ibm.com>

tests/conftest.py

@@ -46,6 +46,7 @@
 @pytest.fixture(scope='session')
 def celery_config():
     return {
+        'broker_connection_retry_on_startup': True,
         'broker_url': 'redis://localhost:6379',
         'result_backend': 'redis://localhost:6379'
     }