Bump docutils from 0.16 to 0.20.1

Bumps [docutils](https://docutils.sourceforge.io/) from 0.16 to 0.20.1.

---
updated-dependencies:
- dependency-name: docutils
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

requirements.txt

@@ -1,6 +1,6 @@
 default-values>=0.5.0
 dict2css>=0.2.3
-docutils==0.16
+docutils==0.20.1
 domdf-python-tools>=2.9.0
 sphinx<3.6.0,>=3.2.0
 sphinx-panels>=0.5.1