[CI] simplification

.gitlab-ci.yml

@@ -60,13 +60,10 @@ linux_docker:
     - source $VENV_DIR/bin/activate
     - pip install --upgrade pip
     - pip install sphinx cloud_sptheme nbsphinx recommonmark numpy
-    - rm -rf artifacts
     - rm -rf public
-    - mkdir artifacts
   script:
     - python setup.py build build_sphinx -b html
-    - mv build/sphinx/html artifacts/doc
-    - mv artifacts/doc public
+    - mv build/sphinx/html public
   after_script:
     - ls -Rl public