fixed the other format string and swapped it to an f-string

test/test_sim_config.py

@@ -60,7 +60,7 @@ def test_root_defaults() -> None:
  found_port = get_simulated_config(config_path, subsys)["port"]
  assert (
  found_port is not None
- ), "Expected port for {} to exist, but found None".format(subsys.name)
+ ), "Expected port for {subsys.name} to exist, but found None"
  assert (
  int(found_port) == expected_port
  ), "Expected to see {expected_port}, but got {found_port}"