.gitlab-ci.yml: Still trying to install pandoc.

.gitlab-ci.yml

 pages:
+  image:
+    name: pandoc
+    entrypoint: ["/bin/sh", "-c"]
+
   script:
   - cd doc
   - pip install nbsphinx nbsphinx_link pydata_sphinx_theme
-  - apt-get install pandoc
   - make html
   - mv _build/html/* ../public/