bpo-45618: Fix documentation build by pinning Docutils version to 0.17.1 (GH-29230)

Co-authored-by: Maciej Olko <maciej.olko@yougov.com>
Co-authored-by: Erlend Egeberg Aasland <erlend.aasland@innova.no>

Author: 3 people

Doc/requirements.txt

@@ -4,6 +4,10 @@
 # won't suddenly cause build failures. Updating the version is fine as long
 # as no warnings are raised by doing so.
 sphinx==3.2.1
+# Docutils version is pinned to a version compatible with Sphinx
+# version 3.2.1. It can be removed after bumping Sphinx version to at
+# least 3.5.4.
+docutils==0.17.1
 
 blurb