chore: rename api_key to hf_token

[NickCrews]

The param name changed in the past but these comments and error messages are stale.

Closes: NA

[gradio-pr-bot]

🪼 branch checks and previews

•	Name	Status	URL
🦄	Changes	detected!	Details
📓	Notebooks	not matching!	Details

---

The demo notebooks don't match the run.py files. Please run this command from the root of the repo and then commit the changes:

pip install nbformat && cd demo && python generate_notebooks.py

[gradio-pr-bot]

🦄 change detected

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gradio	minor

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chore: rename api_key to hf_token

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[abidlabs]

LGTM, thanks @NickCrews for the contribution! I also updated a few of our demo notebooks and added here.

[NickCrews]

Good catch, thank you!