updated CI/CD workflows

[d-kleine]

Description

This PR updates the GitHub Actions workflow to reference the latest versions of actions used in the steps section under uses. These updates aim to improve performance, security, and compatibility with the latest GitHub Actions features.

No major changes were made to the logic of the workflow itself, only version updates. Future updates should follow this format to maintain consistency across workflows. Workflows still use Python 3.9.

Related issues or pull requests

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Pull Request Checklist

• Added a note about the modification or contribution to the ./docs/sources/CHANGELOG.md file (if applicable)
• Added appropriate unit test functions in the ./mlxtend/*/tests directories (if applicable)
• Modify documentation in the corresponding Jupyter Notebook under mlxtend/docs/sources/ (if applicable)
• Ran PYTHONPATH='.' pytest ./mlxtend -sv and make sure that all unit tests pass (for small modifications, it might be sufficient to only run the specific test file, e.g., PYTHONPATH='.' pytest ./mlxtend/classifier/tests/test_stacking_cv_classifier.py -sv)
• Checked for style issues by running flake8 ./mlxtend

[rasbt]

LGTM! Thanks!