latest sphinx seems broken

.gitlab-ci.yml

 #image: registry.esss.lu.se/ics-docker/miniconda
-image: python:3.7-slim
+image: python:3.8-slim
 .pip_install_default: &pip_install_default
     - apt update
     - apt install git -y
     - pip install scipy matplotlib h5py webdavclient3
 .pip_install_sphinx: &pip_install_sphinx
-    - pip install sphinx sphinxcontrib-confluencebuilder sphinxcontrib-blockdiag blockdiag sphinxcontrib-restbuilder sphinx_rtd_theme numpy m2r2
+    - pip install sphinx==3.2.1 sphinxcontrib-confluencebuilder sphinxcontrib-blockdiag blockdiag sphinxcontrib-restbuilder sphinx_rtd_theme numpy m2r2
 variables:
   TWINE_REPOSITORY_URL: https://artifactory.esss.lu.se/artifactory/api/pypi/ics-pypi