[ci] Allow to trigger the documentation job

Even if the release stage is not complete
In case PyPI release job is not trigger on the tag based pipeline
https://docs.gitlab.com/ee/ci/yaml/#needs

.gitlab-ci.yml

@@ -143,3 +143,4 @@ pages:
     - if: $CI_COMMIT_BRANCH == "master"
       when: manual
     - when: never
+  needs: []