ci: don't fail pytest on incomplete coverage

[dkrako]

Problem

Currently, if a PR doesn't achieve full test coverage, all pytest workers will fail. This is not nice, as pytest workers failing should signal errors in tests not in coverage. We already have codecov workers which fail on not meeting 100% coverage.

Solution

I have added the codecov checks to the required checks that each PR must pass. This way we still guarantee that PRs won't be merged with incomplete test coverage, but pytest workers also won't get red.

[codecov[bot]]

Codecov Report

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

Comparison is base (4605d97) 100.00% compared to head (b06b6d9) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #625 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 53 53 Lines 2388 2388 Branches 599 599 ========================================= Hits 2388 2388 ```

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