github actions: Install pytest-cov plug-in

.github/workflows/test.yml

@@ -52,7 +52,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install flake8 pytest coverage toml pint
+          pip install flake8 pytest pytest-cov coverage toml pint
           if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
       - name: Install coverage-lcov
         if: "! inputs.skip-coverage"