ci: update GitHub actions versions

[alexander-held]

Update actions versions of checkout, setup-python and codecov. Temporarily skip black in CI, to be fixed via #458 afterwards (needs update to match latest style).

* update checkout and setup-python actions

* update codecov version and add verbose tag

* temporarily skip black

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (e6ac3e1) 100.00% compared to head (a69be87) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #459 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 22 22 Lines 2082 2082 Branches 340 340 ========================================= Hits 2082 2082 ```

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