ci: another try, install module

.github/workflows/ci.yml

@@ -38,6 +38,7 @@ jobs:
           python -m pip install --upgrade pip
           pip install flake8 pytest pytest-mock pytest-cov mypy types-protobuf
           pip install --use-pep517 -r requirements.txt
+          pip install --no-deps .
       - name: Lint with flake8
         run: |
           # stop the build if there are Python syntax errors or undefined names