Pin docutils on Python 3.9 to override the Zope pin.

versions.cfg

@@ -262,6 +262,7 @@ wsproto = 1.2.0
 
 [versions:python39]
 backports.tarfile = 1.2.0
+docutils = 0.21.2
 
 [versions:python310]
 backports.tarfile = 1.2.0
@@ -273,3 +274,6 @@ backports.tarfile = 1.2.0
 # keep this alphabetical please
 selenium =
     robotframework-seleniumlibrary 6.1.0 is incompatible with 4.10.0. See https://github.com/robotframework/SeleniumLibrary/issues/1835
+docutils =
+    On python39 Zope pins docutils to 0.20.1 because Sphinx <8 requires docutils <0.21 (and Spinx 8 requires Python 3.10+).
+    But we pull in readme-renderer>=35.0 which depends on docutils>=0.21.2.