test_config: fix the bug that will generate !!python/unicode
As an example, [7964999 example_test_002_](https://gitlab.espressif.cn:6688/espressif/esp-idf/-/jobs/7964999/artifacts/file/examples/test_configs/example_test_002_.yml)
@@ -62,4 +62,4 @@ class Job(dict):
file_name = os.path.join(file_path, self["name"] + ".yml")
if "case group" in self:
with open(file_name, "w") as f:
- yaml.dump(self["case group"].output(), f, default_flow_style=False)
+ yaml.safe_dump(self["case group"].output(), f, encoding='utf-8', default_flow_style=False)
