Update the version of pytest

[gmmajal]

Relevant issue: #114

Background info: # any relevant background info for additional context, references to documentations etc.

• There is a new major version of pytest available. We should upgrade to it. Furthermore, we should bump it's associated pluggins to more recent versions.
• There are legacy files including conftest.py and .coveragerc, which were needed during the initial versions of stwfsapy. Our repo structure has since changed and both of these files are no longer needed. Therefore, a cleanup is needed.

Changes introduced: # list changes to the code repo made in this pull request

• The packages: pytest and pytest-mock have been upgraded.
• A new uv.lock file has been generated.
• The conftest.py file and .coveragerc file have been removed.
• The uv pytest command inside the ci.yml has been modified to match the command we use in the github workflows insidequalle, for the sake of consistency.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (66cb62e) to head (29dbdbe).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##            master      #137     +/-   ##
===========================================
  Coverage   100.00%   100.00%             
===========================================
  Files           16        55     +39     
  Lines          940      2722   +1782     
===========================================
+ Hits           940      2722   +1782     

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