SW-828: fixed typo

SAS/OTDB_Services/test/t_TreeStatusEvents.py

@@ -44,7 +44,7 @@ with OTDBTestInstance('t_TreeStatusEvents.in.unittest_db.dump.gz') as test_db:
         with tmp_exchange.create_temporary_queue() as tmp_queue:
             with tmp_queue.create_frombus() as frombus:
 
-                t = threading.Thread(target=create_service, args=(tmp_exchange.address, test_db.dbcreds, '/dev/nullz'))
+                t = threading.Thread(target=create_service, args=(tmp_exchange.address, test_db.dbcreds, '/dev/null'))
                 t.daemon = True
                 t.start()