Bump docutils from 0.17.1 to 0.18

Bumps [docutils](http://docutils.sourceforge.net/) from 0.17.1 to 0.18.

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -1,6 +1,6 @@
 -e .
 black==21.9b0; implementation_name=="cpython"
-docutils==0.17.1
+docutils==0.18
 flake8==4.0.1
 isort==5.9.3
 mypy==0.910; implementation_name=="cpython"