Upgrade Setup-Python GitHub Action

[mdapena]

Initial Checks

• The code compiles successfully without any errors or warnings.
• I have personally tested these changes on my local environment.
• I have ensured that relevant documentation has been added or updated.
• I adhere to the project structure and code standards defined in the documentation.
• My code follows the established coding style guidelines.
• I have added tests for the new code (if applicable).
• All existing tests have passed successfully.

Description

This PR upgrades the Setup-Python GitHub Action from version 4 to version 5 in all workflows. Additionally, it adds a welcome title to the index.md page.