upload the coverage report of all tests, not just of the pytorch tests

[jrasko]

Description

I just noticed that the code coverage displayed by codecov is not correct. Currently, we run our tests in three stages in the pipeline:

1. Tests without pytorch and pypsa (which are most of the tests)
2. Pypsa Tests
3. Pytorch tests

But we only upload the coverage report of step 3 to codecov.
This PR runs all tests in step three, which produces a correct coverage report with the disadvantage of a longer program runtime

It would also be possible to create three different reports and to merge them (see this stack overflow question), but this requires another dependency

Checklist

• Consent to release this PR's code under the GNU Affero General Public License v3.0

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.31%. Comparing base (108dedc) to head (ecf1ee5).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #702       +/-   ##
===========================================
+ Coverage   45.61%   81.31%   +35.69%     
===========================================
  Files          54       54               
  Lines        8032     8032               
===========================================
+ Hits         3664     6531     +2867     
+ Misses       4368     1501     -2867     

Flag	Coverage Δ
pytest	81.31% <ø> (+35.69%)	⬆️

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[maurerle]

Great, this was introduced in #670 but was wrong.
Thanks!

[maurerle]

Btw what is codecov doing if not warning about this here..???
#670 (comment)
Sure, codebase lost 30% coverage sets a green mark