CI add stage: deploy

.gitlab-ci.yml

 image: beagle/sphinx-build-env:latest
 
 on_latest:
+  stage: deploy
   script:
   - rm -rf public
   - sphinx-build -b html . public
@@ -14,6 +15,7 @@ on_latest:
     - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
 
 on_branch:
+  stage: deploy
   script:
   - sphinx-build -b html . public/$CI_COMMIT_BRANCH/
   - sphinx-build -M latexpdf . public/$CI_COMMIT_BRANCH/
@@ -27,6 +29,7 @@ on_branch:
     - if: ($CI_COMMIT_BRANCH && ($CI_COMMIT_BRANCH != $CI_DEFAULT_BRANCH))
 
 on_tag:
+  stage: deploy
   script:
   - export GIT_BRANCH=$(git branch -a --contains tags/$CI_COMMIT_TAG | grep origin | sed 's/.*origin\///')
   - sphinx-build -b html . public/$GIT_BRANCH/