chore(deps): update markdown requirement in /docs/_build

Updates the requirements on [markdown](https://github.com/Python-Markdown/markdown) to permit the latest version.
- [Release notes](https://github.com/Python-Markdown/markdown/releases)
- [Changelog](https://github.com/Python-Markdown/markdown/blob/master/docs/changelog.md)
- [Commits](https://github.com/Python-Markdown/markdown/compare/3.2.1...3.6)

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

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

docs/_build/requirements.txt

@@ -3,7 +3,7 @@ click==8.1.7
 ghp-import==2.1.0
 importlib-metadata==7.0.2
 Jinja2==3.1.3
-Markdown>=3.2.1,<3.6
+Markdown>=3.2.1,<3.7
 MarkupSafe==2.1.5
 mergedeep==1.3.4
 mkdocs==1.5.3