build: Bump dependency on docutils to v0.20.1.

Author: seifertm

dependencies/docs/constraints.txt

@@ -2,7 +2,7 @@ alabaster==0.7.16
 Babel==2.15.0
 certifi==2024.7.4
 charset-normalizer==3.3.2
-docutils==0.18.1
+docutils==0.20.1
 idna==3.7
 imagesize==1.4.1
 Jinja2==3.1.4