Revert "Merge pull request #35 from splitwise/dependabot/bundler/rack-2.2.3"

This reverts commit 421fb40, reversing
changes made to fa9b02d.

Author: rofreg

Gemfile.lock

@@ -91,7 +91,7 @@ GEM
       activesupport (>= 3.1)
     parallel (1.12.1)
     public_suffix (3.0.3)
-    rack (2.2.3)
+    rack (2.0.8)
     rb-fsevent (0.10.3)
     rb-inotify (0.9.10)
       ffi (>= 0.5.0, < 2)