Fixes the `favicon_path` working error

[ShruAgarwal]

Description

Trying to fix the bug related to favicon_path which doesn't seem to work when using it as a path for gradio.mount_gradio_app and FastAPI.

I've made the appropriate changes as suggested by @freddyaboulton on the issue:

""" It would be here:

https://github.com/gradio-app/gradio/blob/94a1143686733c7fe16e204764b9a3e7240ccf02/gradio/routes.py#L1222

We want to output a warning if favicon_path is not None and the path is not / """

Closes: #8137

🎯 PRs Should Target Issues

Before your create a PR, please check to see if there is an existing issue for this change. If not, please create an issue before you create this PR, unless the fix is very small.

Not adhering to this guideline will result in the PR being closed.

Tests

1. PRs will only be merged if tests pass on CI. To run the tests locally, please set up your Gradio environment locally and run the tests: bash scripts/run_all_tests.sh

2. You may need to run the linters: bash scripts/format_backend.sh and bash scripts/format_frontend.sh

[gradio-pr-bot]

🪼 branch checks and previews

•	Name	Status	URL
	Spaces	ready!	Spaces preview
	Website	ready!	Website preview
:unicorn:	Changes	detecting...

---

Install Gradio from this PR

pip install https://gradio-builds.s3.amazonaws.com/3677066afcb0f9333b65381fd11b55ee2b073bb1/gradio-4.36.1-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@3677066afcb0f9333b65381fd11b55ee2b073bb1#subdirectory=client/python"

Install Gradio JS Client from this PR

npm install https://gradio-builds.s3.amazonaws.com/3677066afcb0f9333b65381fd11b55ee2b073bb1/gradio-client-1.1.1.tgz

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
gradio	patch

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

With the following changelog entry.

Fixes the favicon_path working error

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](https://github.com/ShruAgarwal/gradio/edit/main/.changeset/red-badgers-sip.md).