try conda

.gitlab-ci.yml

 pages:
   script:
-  - apk add --repository https://dl-cdn.alpinelinux.org/alpine/edge/community pandoc
-  - pip install -r requirements.txt
-  - pip install cartopy
-  - pip install nbsphinx nbsphinx_link pydata_sphinx_theme sphinx_copybutton
+  - conda env create -f ci/requirements_py311.yml
+  - conda activate pyicon_py311
   - pip install -e .
   - cd doc
   - make html
   - mv _build/html/* ../public/
 
   tags:
-  - sphinx
+  - conda
 
   only:
   - master

ci/requirements_py311.yml

+name: pyicon_py311
+channels:
+  - conda-forge
+dependencies:
+  - python=3.11
+  - numpy
+  - dask
+  - matplotlib
+  - cartopy
+  - netcdf4
+  - xarray
+  - zarr
+  - pandas
+  - cmocean
+  - scipy
+  - ipdb
+  - ipywidgets
+  - jupytext
+  - pytest
+  - healpy
+  - pandoc
+  - sphinx  # Documentation
+  - nbsphinx  # Documentation
+  - nbsphinx-link  # Documentation
+  - sphinx-copybutton  # Documentation
+  - pydata-sphinx-theme  # Documentation