Fix PytestRemovedIn8Warning ("support for nose tests is deprecated and will be removed in a future release")

[muxator]

Before this change, the test log contained 37 entries like this:

PytestRemovedIn8Warning: Support for nose tests is deprecated and will be removed in a future release.

After this change, on my machine the test log shrinks from 1672 to 1405 lines (16% less).

At some point in time, we will migrate to Pytest 8.x, and this would be an hindrance.

A reference for the fix can be found at https://docs.pytest.org/en/stable/deprecations.html#support-for-tests-written-for-nose

Affected tests were found with: rg "def (setup|teardown)\(" tests

Please merge this after #82 (migration to python 3.12).

[codecov-commenter]

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Codecov Report

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

Project coverage is 88.52%. Comparing base (c5f8eb7) to head (d1473a9).

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Additional details and impacted files

[](https://app.codecov.io/gh/bancaditalia/black-it/pull/84?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) ```diff @@ Coverage Diff @@ ## main #84 +/- ## ========================================== + Coverage 83.91% 88.52% +4.60% ========================================== Files 32 33 +1 Lines 1716 1751 +35 ========================================== + Hits 1440 1550 +110 + Misses 276 201 -75 ``` [see 3 files with indirect coverage changes](https://app.codecov.io/gh/bancaditalia/black-it/pull/84/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None)

[AldoGl]

This LGTM, feel free to merge!