chore(deps): bump markdown in /backend in the python group

Bumps the python group in /backend with 1 update: [markdown](https://github.com/Python-Markdown/markdown).


Updates `markdown` from 3.6 to 3.7
- [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@3.6...3.7)

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

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

backend/requirements.txt

@@ -37,7 +37,7 @@ drf-writable-nested==0.7.0
     # via -r requirements.in
 gunicorn==23.0.0
     # via -r requirements.in
-markdown==3.6
+markdown==3.7
     # via -r requirements.in
 packaging==23.1
     # via gunicorn