Fix OS detection for cross-browser compatibility

[lappemic]

This PR addresses part of the issue described in #8736, where Slider Component Demos and some UI elements were not working correctly in Firefox and Safari.

Changes made:

• Replaced the use of navigator.userAgentData with a more compatible get_os() function
• Updated the logic for setting the meta_key based on the detected OS

These changes improve compatibility across different browsers, particularly Firefox and Safari. The new implementation:

• Fixes the functionality of tabs and the "Open in..." button in Firefox and Safari
• Resolves the demo loading issue in Safari

Note: The demo in Firefox still requires further investigation.

To test:

1. Check the functionality of tabs and the "Open in..." button in Firefox and Safari
2. Verify that the demo loads correctly in Safari
3. Confirm that the correct keyboard shortcut (⌘+K for Mac/iOS, CTRL+K for others) is displayed

If anyhone knows how to address the Firefox demo issue i would love to fix this as well.

[gradio-pr-bot]

🪼 branch checks and previews

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

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Install Gradio from this PR

pip install https://gradio-builds.s3.amazonaws.com/b3369ca18539a4e2c697bebab2441de574b54937/gradio-4.38.1-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@b3369ca18539a4e2c697bebab2441de574b54937#subdirectory=client/python"

Install Gradio JS Client from this PR

npm install https://gradio-builds.s3.amazonaws.com/b3369ca18539a4e2c697bebab2441de574b54937/gradio-client-1.3.0.tgz

[gradio-pr-bot]

🦄 change detected

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website	minor

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With the following changelog entry.

Fix OS detection for cross-browser compatibility

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[aliabd]

Thanks @lappemic! Changes look good to me.

I'll continue to debug what's going on with demos on firefox.