Update langtrace_mistral.ipynb source

[emmanuel-ferdman]

Cookbook Pull Request

Description

This small PR fixes the langtrace_mistral.ipynb source in README.md.

Type of Change

What type of PR is it?

• New Cookbook
  • Notebook File
    • Does it work on google colab?
  • Markdown File
• Cookbook Update
  • Code Refactoring
  • Bug Fix
• README.md Update

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• Other (please describe):

Cookbook Checklist:

• My code is easy to read and well structured.
• I've tagged the versions of any dependency required.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• My changes generate no new warnings or errors.

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• My changes do not concern the cookbooks.

README.md Checklist

• I've added my cookbook to the table.

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• My changes do not concern the README file.

Additional Context

Add any other context or screenshots about the feature request here.

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[emmanuel-ferdman]

@pandora-s-git could you please review this small PR when you get the chance? thanks! 🙌