build(deps): bump markdown from 3.7 to 3.8.1 in /docs

Bumps [markdown](https://github.com/Python-Markdown/markdown) from 3.7 to 3.8.1.
- [Release notes](https://github.com/Python-Markdown/markdown/releases)
- [Changelog](https://github.com/Python-Markdown/markdown/blob/master/docs/changelog.md)
- [Commits](Python-Markdown/markdown@3.7...3.8.1)

---
updated-dependencies:
- dependency-name: markdown
  dependency-version: 3.8.1
  dependency-type: direct:production
...

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

Author: dependabot[bot]

docs/requirements.txt

@@ -8,7 +8,7 @@ colorama==0.4.6
 ghp-import==2.1.0
 idna==3.10
 Jinja2==3.1.6
-Markdown==3.7
+Markdown==3.8.1
 MarkupSafe==3.0.2
 mergedeep==1.3.4
 mkdocs==1.6.1