Merge pull request #186 from buildpacks/dependabot/bundler/apps/ruby-bundler/rack-2.2.8.1

Bump rack from 2.2.6.4 to 2.2.8.1 in /apps/ruby-bundler

Author: AidanDelaney

apps/ruby-bundler/Gemfile.lock

@@ -3,7 +3,7 @@ GEM
   specs:
     mustermann (1.1.1)
       ruby2_keywords (~> 0.0.1)
-    rack (2.2.6.4)
+    rack (2.2.8.1)
     rack-protection (2.2.0)
       rack
     ruby2_keywords (0.0.5)