cpython/Doc/requirements.txt

# Requirements to build the Python documentation

# Sphinx version is pinned so that new versions that introduce new warnings
# won't suddenly cause build failures. Updating the version is fine as long
# as no warnings are raised by doing so.
sphinx==2.4.4

blurb

# The theme used by the documentation is stored separately, so we need
# to install that as well.
python-docs-theme