ci(tests): Run black --check

Author: tony

.github/workflows/tests.yml

@@ -56,6 +56,9 @@ jobs:
       run: |
         poetry install -E "test coverage lint"
 
+    - name: Lint with black . --check
+      run: poetry run black . --check
+
     - name: Lint with ruff .
       run: poetry run ruff .