Implement JSON dump conversion for torch_dtype in TrainingArguments
Author: junrae6454
Pull request: yes

# What does this PR do?
- Implement JSON dump conversion for torch_dtype in TrainingArguments and address TRL serialization issue when logging
- JSON dump conversion for torch_dtype in TrainingArguments: This functionality ensures that the TrainingArguments object can be properly serialized and saved to a JSON file.


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Fixes # (issue)


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Comments:
cc @muellerzr @SunMarc 

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_31224). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

I am a beginner with unittest.
If this test does not match the intended use, I would appreciate any corrections or suggestions.

Thanks to @muellerzr @SunMarc 🤗

Thank you @amyeroberts for your feedback!