The docs build failure in #337 / https://readthedocs.org/projects/histolab/builds/15130445/ is likely due to using an old version of Sphinx (1.8.5) which isn't compatible with the new docutils 0.18 release.

The newest Sphinx (4.2.0) isn't either, but it pins to a compatible docutils.

See sphinx-doc/sphinx#9727.