tests: add durations argument to pytest config

[johannaSommer]

Description

This PR extends the newly introduced pytest configuration in the pyproject.toml with the duration argument, which helps us keep track of the computation time on some experiments. Specifically for the CPU tests run on GitHub action, we will use this to determine which tests will be marked as pytest.mark.slow, meaning they will only run during the nightly tests.

Related Issue

None.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Verified updated logging locally.

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 made corresponding changes to the documentation
• 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

Additional Notes

None.

[nifleisch]

LGTM 🙌