ci: add black linting

.gitlab-ci.yml

@@ -10,6 +10,7 @@
     ref: "branch/default"
     file:
       - "templates/no-duplicated-ci-pipelines.yml"  # use workflow to avoid duplicated pipelines
+      - "templates/lint/black.yml"
       - "templates/lint/flake8.yml"  # will do the equivalent of 'tox -e flake8'
       - "templates/lint/check-manifest.yml"  # will do the equivalent of 'tox -e check-manifest'
       - "templates/lint/yamllint.yml"  # will do the equivalent of 'tox -e yamllint'