Update docutils requirement from <0.19 to <0.20 (#348)

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] <[email protected]>

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pyproject.toml

@@ -52,7 +52,7 @@ Tracker = "https://github.com/jupyterlab/jupyterlab_server/issues"
 [project.optional-dependencies]
 docs = [
   "autodoc-traits",
-  "docutils<0.19",
+  "docutils<0.20",
   "pydata_sphinx_theme",
   "sphinx",
   "sphinx-copybutton",