add black to github actions

.github/workflows/python-linting.yml

@@ -23,12 +23,13 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install flake8 pytest
+        pip install flake8 pytest black
         if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
-    - name: Lint with flake8
+    - name: Lint with flake8 & black
       run: |
         # stop the build if there are Python syntax errors or undefined names
         flake8 SwagLyricsBot --count --max-line-length=120 --max-complexity=10 --show-source --statistics
+        black -l 120 --check --diff .
 #     - name: Test with pytest
 #       run: |
 #         pytest