Fix: Remove duplicated comma in distributed_inference.md

[vahidaskari]

What does this PR do?

This commit removes a duplicated comma in distributed_inference.md, which causes syntax error.

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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  here are tips on formatting docstrings.
• Did you write any new necessary tests?

Who can review?

@stevhliu @sayakpaul

[sayakpaul]

Thanks!

[HuggingFaceDocBuilderDev]

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