Make pytest . a mandatory test

Author: cclauss

.github/workflows/lint_python.yml

@@ -14,6 +14,6 @@ jobs:
       - run: isort --profile black .
       - run: tox
       - run: pip install -e .
-      - run: pytest . || true
+      - run: pytest .
       - run: pytest --doctest-modules . || true
       - run: shopt -s globstar && pyupgrade --py36-plus **/*.py || true