enforce formatting checks

.github/workflows/python-package.yml

@@ -28,6 +28,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         python -m pip install flake8 pytest
+        python -m pip install black
         if [ -f requirements-dev.txt ]; then pip install -r requirements-dev.txt; fi
     - name: Install software
       run: |
@@ -36,8 +37,10 @@ jobs:
       run: |
         # stop the build if there are Python syntax errors or undefined names
         flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
-        # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
-        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+        flake8 . --count --max-complexity=10 --max-line-length=120 --statistics
+    - name: Check code formatting with black
+      run: |
+        black --check .
     - name: Run unittests
       run: |
         python -m pytest