Bump markdown from 3.3.7 to 3.4.4

Bumps [markdown](https://github.com/Python-Markdown/markdown) from 3.3.7 to 3.4.4.
- [Changelog](https://github.com/Python-Markdown/markdown/blob/master/docs/change_log/release-2.6.md)
- [Commits](Python-Markdown/markdown@3.3.7...3.4.4)

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

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

requirements.txt

@@ -1,4 +1,4 @@
-Markdown==3.3.7
+Markdown==3.4.4
 mike==1.1.2
 mkdocs-git-revision-date-plugin==0.3.2
 mkdocs-macros-plugin==1.0.2