Bump markdown from 3.4.4 to 3.5.1 (#168)

Bumps [markdown](https://github.com/Python-Markdown/markdown) from 3.4.4 to 3.5.1.
- [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/3.4.4...3.5.1)

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

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

requirements.txt

@@ -1,7 +1,7 @@
 beautifulsoup4==4.12.2
 cffi==1.16.0
 html5lib==1.1
-Markdown==3.4.4
+Markdown==3.5.1
 mwparserfromhell==0.6.5
 pycparser==2.21
 pygit2==1.13.2