Merge branch 'show-diff' into 'main'

Make black actually show what it would like to have changed

See merge request templates/python-package!2

.gitlab-ci.yml

@@ -30,7 +30,7 @@ run_black:
   stage: lint
   script:
     - python -m black --version
-    - python -m black --check .
+    - python -m black --check --diff .
   allow_failure: true
 
 run_flake8: