Bump markdown from 3.5 to 3.5.1

Bumps [markdown](https://github.com/Python-Markdown/markdown) from 3.5 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](Python-Markdown/markdown@3.5...3.5.1)

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

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

requirements/base.txt

@@ -8,7 +8,7 @@ django-guardian==2.4.0
 django-userena-ce==7.0.3
 easy-thumbnails==2.8.5
 python-postmark==0.6.0
-Markdown==3.5
+Markdown==3.5.1
 Pillow==10.1.0
 raven==6.10.0
 icalendar==5.0.10