Bump kramdown from 2.3.0 to 2.3.1

Bumps [kramdown](https://github.com/gettalong/kramdown) from 2.3.0 to 2.3.1.
- [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[bot] <[email protected]>

Author: dependabot[bot]

Gemfile.lock

@@ -74,7 +74,7 @@ GEM
     jekyll-watch (2.2.1)
       listen (~> 3.0)
     json (2.5.1)
-    kramdown (2.3.0)
+    kramdown (2.3.1)
       rexml
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
@@ -124,7 +124,7 @@ GEM
 
 PLATFORMS
   ruby
-  x86_64-linux-musl
+  x86_64-linux
 
 DEPENDENCIES
   dotenv