Bump kramdown from 2.5.1 to 2.5.2

Bumps [kramdown](https://github.com/gettalong/kramdown) from 2.5.1 to 2.5.2.
- [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)

---
updated-dependencies:
- dependency-name: kramdown
  dependency-version: 2.5.2
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -1,12 +1,12 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    kramdown (2.5.1)
-      rexml (>= 3.3.9)
+    kramdown (2.5.2)
+      rexml (>= 3.4.4)
     power_assert (3.0.1)
     prettier_print (1.2.1)
     rake (13.3.1)
-    rexml (3.3.9)
+    rexml (3.4.4)
     rouge (4.7.0)
     syntax_tree (6.3.0)
       prettier_print (>= 1.2.0)