specify git user.name and user.email in workflow for tests

Author: timvink

.github/workflows/workflow.yml

@@ -14,6 +14,8 @@ jobs:
         python-version: 3.7
     - name: Generate coverage report
       run: |
+        git config --global user.name "Github Action"
+        git config --global user.email "[email protected]"
         pip install -r tests/test_requirements.txt
         pip install -e .
         pytest --cov=mkdocs_git_revision_date_localized_plugin --cov-report=xml