Merge pull request #2601 from prometheus/dependabot/bundler/rack-2.2.13

Bump rack from 2.2.6.4 to 2.2.13

Author: SuperQ

Gemfile.lock

@@ -104,7 +104,7 @@ GEM
     public_suffix (5.0.1)
     pygments.rb (2.3.1)
     racc (1.6.2)
-    rack (2.2.6.4)
+    rack (2.2.13)
     rb-fchange (0.0.6)
       ffi
     rb-fsevent (0.11.2)