[Security] Bump kramdown from 2.3.0 to 2.3.1 (#1416)

Bumps [kramdown](https://github.com/gettalong/kramdown) from 2.3.0 to 2.3.1. **This update includes a security fix.**
- [Release notes](https://github.com/gettalong/kramdown/releases)
- [Changelog](https://github.com/gettalong/kramdown/blob/master/doc/news.page)
- [Commits](https://github.com/gettalong/kramdown/commits)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Gemfile.lock

@@ -31,7 +31,7 @@ GEM
     hashie (3.6.0)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    kramdown (2.3.0)
+    kramdown (2.3.1)
       rexml
     listen (3.0.8)
       rb-fsevent (~> 0.9, >= 0.9.4)