Remove stable diffusion demo from landing page

[aliabd]

Remove stable diffusion demo from landing page due to issues with embedding it.

[gradio-pr-bot]

🪼 branch checks and previews

•	Name	Status	URL
	Spaces	ready!	Spaces preview
	Website	ready!	Website preview
🦄	Changes	detected!	Details

---

Install Gradio from this PR

pip install https://gradio-builds.s3.amazonaws.com/60f0e99b900af59d618a5e15332b8ab6c09d319a/gradio-3.42.0-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@60f0e99b900af59d618a5e15332b8ab6c09d319a#subdirectory=client/python"

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
website	minor

• Maintainers can select this checkbox to manually select packages to update.

With the following changelog entry.

Remove stable diffusion demo from landing page

Maintainers or the PR author can modify the PR title to modify this entry.

Something isn't right?

• Maintainers can change the version label to modify the version bump.
• If the bot has failed to detect any changes, or if this pull request needs to update multiple packages to different versions or requires a more comprehensive changelog entry, maintainers can update the changelog file directly.

[abidlabs]

thanks @aliabd! we can bring it back once we support embedding Spaces w/ replicas