Merge pull request #239 from zaproxy/dependabot/bundler/rack-2.2.20

Bump rack from 2.2.19 to 2.2.20

Author: thc202

Gemfile.lock

@@ -92,7 +92,7 @@ GEM
     parslet (2.0.0)
     public_suffix (5.0.4)
     racc (1.8.1)
-    rack (2.2.19)
+    rack (2.2.20)
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)