[Dependabot]: Update docutils requirement

Updates the requirements on [docutils](https://docutils.sourceforge.io/) to permit the latest version.

---
updated-dependencies:
- dependency-name: docutils
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

doc/requirements.txt

@@ -5,7 +5,7 @@ colorama >= 0.4.6
 
 # Enforce latest version on ReadTheDocs
 sphinx >= 7.2, < 8.0
-docutils >= 0.18.0, < 0.19.0
+docutils >= 0.18.0, < 0.21.0
 
 # ReadTheDocs Theme
 sphinx_rtd_theme ~= 2.0.0