build(deps): update markdown requirement from ~=3.2 to ~=3.6 (#2881)

Updates the requirements on [markdown](https://github.com/Python-Markdown/markdown) to permit the latest version.
- [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@3.2...3.6)

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

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

Author: dependabot[bot]

requirements.txt

@@ -5,7 +5,7 @@ jsmin==3.0.1
 livereload==2.6.3
 # mkdocs 2.4.1 requires Markdown < 3.4.0
 # https://github.com/kubernetes-sigs/gateway-api/pull/1671#issuecomment-1400586465
-markdown~=3.2
+markdown~=3.6
 MarkupSafe==2.1.5
 mkdocs==1.5.3
 mkdocs-awesome-pages-plugin==2.9.2