attribute ValueError in llama3 models export

**Describe the bug:**

The export of llama3 models is broken under this version 0.8.1.

ERROR: fairseq2 - Command failed due to an unexpected error. See logged stack trace for details and file a bug report to the corresponding author.
Traceback (most recent call last):
fairseq2/models/utils/hg_export.py", line 69, in main
_run()

fairseq2/models/utils/hg_export.py", line 107, in _run
export_command.run(args.model, args.save_dir) # save_dir is Path

fairseq2/models/utils/hg_export.py", line 286, in run
self._hg_saver(tmp_save_dir, hg_state_dict, hg_config)

fairseq2/models/hg/converter.py", line 178, in save_hugging_face_model
raise ValueError(
ValueError: `transformers.LlamaConfig` does not have an attribute named rope_theta.

**Describe how to reproduce:**
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**Describe the expected behavior:**
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**Environment:**
At the very least, specify the versions of fairseq2, PyTorch, Python, and CUDA along with your operating system and, if relevant, GPU model.

**Additional Context:**
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