Add doc-string linting with velin

.gitlab-ci.yml

@@ -110,13 +110,7 @@ run-doc-test:
   script:
     - pip install -r requirements_doc.txt
     - sphinx-build -b html docs_sphinx public
-
-run-lint:
-  variables:
-    QT_API: pyside2
-  image: python:3.10
-  stage: test
-  script:
+    # Run linting on doc-strings
     - pip install black velin
     - velin . --check --black