fix turn-detector loading issue due to transformers 4.57.2

[longcw]

temporally fix turn detector loading issue introduced by transformers 4.57.2

Could not find model livekit/turn-detector with revision v0.4.1-intl. Make sure you have downloaded the model before running the agent. Use `python3 your_agent.py download-files` to download the models.
error initializing inference runner
Traceback (most recent call last):
  File "/Users/darryncampbell/temp/agent-starter-python/.venv/lib/python3.13/site-packages/livekit/agents/ipc/inference_proc_lazy_main.py", line 69, in initialize
    runner.initialize()
    ~~~~~~~~~~~~~~~~~^^
  File "/Users/darryncampbell/temp/agent-starter-python/.venv/lib/python3.13/site-packages/livekit/plugins/turn_detector/base.py", line 146, in initialize
    raise RuntimeError(
    ...<2 lines>...
    ) from None
RuntimeError: livekit-plugins-turn-detector initialization failed. Could not find model livekit/turn-detector with revision v0.4.1-intl.

related to huggingface/transformers#42369

the issue was caused by this change https://github.com/huggingface/transformers/pull/42299/files#diff-85b29486a884f445b1014a26fecfb189141f2e6b09f4ae701ee758a754fddcc1R2102, we set local_files_only=True and the pretrained_model_name_or_path is the repo name livekit/turn-detector, it goes to remote_files = os.listdir(pretrained_model_name_or_path) which raises the file not found error

[chenghao-mou]

LGTM