hotfix vscode pytest-xdist issues (#87) (#101)

Addresses issues caused by #89, mentioned in #87 
by disabling parallel testing for now.

We still test in parallel in the CI.
We still install pytest-xdist.

Any developer not having issues with parallel testing can add "-n auto" 
in their vscode pytest settings as an additional argument to still use parallel test execution.

.github/workflows/pytest.yml

@@ -36,7 +36,7 @@ jobs:
       - name: Run PyTest
 
         run: |
-          pytest --junitxml=pytest.xml --cov-report=term-missing:skip-covered --cov=mrpro | tee pytest-coverage.txt
+          pytest -n 4 --junitxml=pytest.xml --cov-report=term-missing:skip-covered --cov=mrpro | tee pytest-coverage.txt
 
       - name: Pytest coverage comment
         id: coverageComment

pyproject.toml

@@ -51,7 +51,7 @@ docs = ["sphinx", "sphinx_rtd_theme"]
 [tool.pytest.ini_options]
 testpaths = ["tests"]
 filterwarnings = ["error"]
-addopts = "-n auto"
+# addopts = "-n auto" # TODO: debug vscode missing tests if enabled
 
 # MyPy section
 [tool.mypy]