Removing Gitlab CI yml file

.gitlab-ci.yml

-image: python:3.7-alpine
-
-build_sphinx:
-  stage: build
-  tags:
-    - hpvm
-  script:
-    - pip install -U sphinx sphinx-autodoc-typehints sphinx-rtd-theme numpydoc
-    - sphinx-build -b html hpvm/docs/ public/
-  artifacts:
-    paths:
-    - public