Bump markdown from 3.8 to 3.8.1 (#298)

Bumps [markdown](https://github.com/Python-Markdown/markdown) from 3.8 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@3.8...3.8.1)

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

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

Author: dependabot[bot]

requirements.txt

@@ -33,7 +33,7 @@ jupyter_client==8.6.3
 jupyter_core==5.8.1
 jupyterlab_pygments==0.3.0
 jupytext==1.17.2
-Markdown==3.8
+Markdown==3.8.1
 markdown-it-py==3.0.0
 MarkupSafe==3.0.2
 matplotlib-inline==0.1.7