use sphinx-lint -i venv in gitlab ci

.gitlab-ci.yml

@@ -59,7 +59,7 @@ pages_test:
   script:
     # install documentation requirements
     - pip install -r ./docs/requirements.txt
-    - sphinx-lint
+    - sphinx-lint -i venv
     - sphinx-build -W -b html ./docs ./public
   rules:
     - if: $CI_COMMIT_REF_NAME != $CI_DEFAULT_BRANCH