try a warning: problem matcher

Author: altendky

.github/workflows/ci.yml

@@ -101,6 +101,9 @@ jobs:
               tox: qt5
     steps:
       - uses: actions/checkout@v2
+      - name: Enable Problem Matchers
+        run: |
+          echo "::add-matcher::.github/warnings-problem-matchers.json"
       - name: Set up ${{ matrix.python.name }}
         if: ${{ job.container == '' }}
         uses: actions/setup-python@v1