use hub.docker.com beagle/sphinx-build-env

.gitlab-ci.yml

-image: python:3.9-alpine
+image: beagle/sphinx-build-env:latest
 
 stages:
   - deploy
 
-before_script:
-  - apk update
-  - python -m pip install --upgrade pip
-  - pip install -U sphinx
-  - pip install sphinxcontrib-svg2pdfconverter
-  - apk add librsvg
-  - pip install sphinx_rtd_theme
-  - apk add texlive-full
-  - apk add make
-
 pages:
   stage: deploy
   script: