Add missing tf_keras to req.txt

[JasonZhu1313]

Summary

Add missing tf_keras to req.txt

Add missing tf_keras to req.txt , otherwise pip install -r requirement.txt and then run the script will result in

ValueError: Your currently installed version of Keras is Keras 3, but this is not yet supported in Transformers. Please install the backwards-compatible tf-keras package with `pip install tf-keras`.

Testing Done

Done

• Hardware Type:
• run make test to ensure correctness
• run make checkstyle to ensure code style
• run make test-convergence to ensure convergence