Address warning in GitHub Actions tests about deprecated action

[tleonhardt]

Address the following warning:

Warning: This action is being deprecated in favor of 'codecov-action'.
Please update CI accordingly to use 'codecov-action@v5' with
'report_type: test_results'.
The 'codecov-action' should and can be run at least once for
coverage and once for test results

[github-actions]

🤖 Hi @tleonhardt, I've received your request, and I'm working on it now! You can track my progress in the logs for more details.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.94%. Comparing base (7635018) to head (0ee8fdf).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1563   +/-   ##
=======================================
  Coverage   98.94%   98.94%           
=======================================
  Files          21       21           
  Lines        4935     4935           
=======================================
  Hits         4883     4883           
  Misses         52       52           

Flag	Coverage Δ
unittests	98.94% <ø> (ø)

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[github-actions]

🤖 I'm sorry @tleonhardt, but I was unable to process your request. Please see the logs for more details.