Switch to pytest for Python unit tests CI

- Use pytest in the GitHub Actions workflow
- Add a pytest configuration file

Author: per1234

.github/workflows/libraries_compile-examples.yml

@@ -32,4 +32,4 @@ jobs:
         run: |
           export PYTHONPATH="$GITHUB_WORKSPACE/libraries/compile-examples/compilesketches:$GITHUB_WORKSPACE/libraries/compile-examples/reportsizetrends"
           pytest "$GITHUB_WORKSPACE/libraries/compile-examples/compilesketches/tests"
-          python -m unittest discover "$GITHUB_WORKSPACE/libraries/compile-examples/reportsizetrends/tests"
+          pytest "$GITHUB_WORKSPACE/libraries/compile-examples/reportsizetrends/tests"

reportsizetrends/requirements.txt

@@ -1,2 +1,3 @@
 google-auth~=1.11
 google-api-python-client~=1.7
+pytest==5.4.1

reportsizetrends/tests/pytest.ini

@@ -0,0 +1,8 @@
+[pytest]
+filterwarnings =
+    error
+    ignore::DeprecationWarning
+    ignore::ResourceWarning
+
+markers =
+    slow: marks tests as slow (deselect with '-m "not slow"')