Bump Github Actions version to silence Node.js version warnings

[IvanIsCoding]

This PR is to address some of the warnings that started showing up, like the following one:

[Build, rustfmt, and python lint]
Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: 
actions/checkout@v3, actions/setup-python@v4, actions/upload-artifact@v3. 
For more information see: 
https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.

[coveralls]

Pull Request Test Coverage Report for Build 7682502917

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 6 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 95.94%

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Files with Coverage Reduction	New Missed Lines	%
src/shortest_path/all_pairs_bellman_ford.rs	6	95.53%

Totals
Change from base Build 7682271447:	-0.04%
Covered Lines:	16636
Relevant Lines:	17340

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💛 - Coveralls