ci: upgrade Actions to use Node 20

[uniqueg]

Description

• Upgrade actions/checkout to v4
• Upgrade actions/setup-python to v5

Fixes #235

Type of change

Please delete options that are not relevant.

• CI update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation (or documentation does not need to be updated)
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have not reduced the existing code coverage

[sourcery-ai]

Hey @uniqueg - I've reviewed your changes and they look great!

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (b1100bc) to head (3345fe1).
Report is 3 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff            @@
##               dev      #236   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           20        20           
  Lines          977       977           
=========================================
  Hits           977       977           

Flag	Coverage Δ
test_unit	100.00% <ø> (ø)

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