Bump redcarpet from 3.5.0 to 3.5.1

Bumps [redcarpet](https://github.com/vmg/redcarpet) from 3.5.0 to 3.5.1.
- [Release notes](https://github.com/vmg/redcarpet/releases)
- [Changelog](https://github.com/vmg/redcarpet/blob/master/CHANGELOG.md)
- [Commits](vmg/redcarpet@v3.5.0...v3.5.1)

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

Author: dependabot[bot]

Gemfile.lock

@@ -317,7 +317,7 @@ GEM
       ffi (>= 1.0.6)
       msgpack (>= 0.4.3)
       optimist (>= 3.0.0)
-    redcarpet (3.5.0)
+    redcarpet (3.5.1)
     redis (3.3.5)
     redis-namespace (1.7.0)
       redis (>= 3.0.4)