Bump rinku from 2.0.5 to 2.0.6

Bumps [rinku](https://github.com/vmg/rinku) from 2.0.5 to 2.0.6.
- [Release notes](https://github.com/vmg/rinku/releases)
- [Commits](vmg/rinku@v2.0.5...v2.0.6)

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

Gemfile.lock

@@ -276,7 +276,7 @@ GEM
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 3.0)
       netrc (~> 0.7)
-    rinku (2.0.5)
+    rinku (2.0.6)
     rollbar (2.19.3)
       multi_json
     ruby-pushbullet (0.1.4)