🧪 Add tests for yaml module registration and functions

[Tcode-Motion]

🎯 What: The yaml.rs file lacked tests for module registration and the core functions (parse and stringify), presenting a gap in test coverage.
📊 Coverage: Test coverage now includes test_register_yaml (testing module registration), test_yaml_parse (verifying proper YAML parsing and formatting), and test_yaml_stringify (verifying maps are correctly serialized to YAML strings).
✨ Result: Increased code reliability and confidence with unit tests guarding against future regressions in the yaml standard library functions.

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PR created automatically by Jules for task 17812475441390110190 started by @Tcode-Motion

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