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

@@ -45,7 +45,7 @@ GEM
       sassc (> 2.0.1, < 3.0)
     jekyll-watch (2.2.1)
       listen (~> 3.0)
-    kramdown (2.3.0)
+    kramdown (2.3.1)
       rexml
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
@@ -76,7 +76,6 @@ GEM
     terminal-table (2.0.0)
       unicode-display_width (~> 1.1, >= 1.1.1)
     unicode-display_width (1.7.0)
-    wdm (0.1.1)
 
 PLATFORMS
   ruby
@@ -89,7 +88,6 @@ DEPENDENCIES
   jekyll-asciidoc
   jekyll-gist
   jekyll-paginate
-  wdm (>= 0.1.0)
 
 BUNDLED WITH
    2.1.4