fix python example in generating-a-json-web-token-jwt-for-a-github-app

[gregsadetsky]

Why:

Closes: #39408

What's being changed (if available, include any code snippets, screenshots, or gifs):

the python example has been fixed

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• The changes in this PR meet the docs fundamentals that are required for all content.
• All CI checks are passing and the changes look good in the review environment.

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[Copilot]

Pull Request Overview

This PR fixes the Python code example in the GitHub App JWT generation documentation to use the correct PyJWT library API. The changes update the outdated jwt module usage to the modern JWT class-based approach with proper key handling.

Key changes:

• Updates import statement to use the modern JWT class and jwk_from_pem function
• Modifies key loading to use jwk_from_pem for proper PEM file handling
• Changes JWT encoding to use the instance-based approach with updated parameter names

[Copilot]

The parameter name change from 'algorithm' to 'alg' should be documented or explained in the surrounding text to help users understand why this change was made, especially since this differs from the previous API.

Suggested change

	instance = JWT()
	instance = JWT()
	# The 'alg' parameter specifies the algorithm used for signing the JWT.
	# It corresponds to the 'algorithm' parameter in the previous API.

[github-actions]

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Source	Review	Production	What Changed
apps/creating-github-apps/authenticating-with-a-github-app/generating-a-json-web-token-jwt-for-a-github-app.md	fpt ghec ghes@ 3.17 3.16 3.15 3.14	fpt ghec ghes@ 3.17 3.16 3.15 3.14

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