Bump rack from 2.0.7 to 2.2.2 in /benchmarks/workloads/ruby

Bumps [rack](https://github.com/rack/rack) from 2.0.7 to 2.2.2.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rack/rack/compare/2.0.7...v2.2.2)

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

benchmarks/workloads/ruby/Gemfile.lock

@@ -1,28 +1,41 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    activemerchant (1.105.0)
+      activesupport (>= 4.2)
+      builder (>= 2.1.2, < 4.0.0)
+      i18n (>= 0.6.9)
+      nokogiri (~> 1.4)
     activesupport (5.2.3)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
+    bcrypt (3.1.13)
+    builder (3.2.4)
     cassandra-driver (3.2.3)
       ione (~> 1.2)
     concurrent-ruby (1.1.5)
+    ffi (1.12.2)
     i18n (1.6.0)
       concurrent-ruby (~> 1.0)
     ione (1.2.4)
+    mini_portile2 (2.4.0)
     minitest (5.11.3)
     mustermann (1.0.3)
+    nokogiri (1.10.8)
+      mini_portile2 (~> 2.4.0)
     pdf-core (0.7.0)
     prawn (2.2.2)
       pdf-core (~> 0.7.0)
       ttfunk (~> 1.5)
     puma (3.12.1)
-    rack (2.0.7)
+    rack (2.2.2)
     rack-protection (2.0.5)
       rack
     rake (12.3.2)
+    rbnacl (7.1.1)
+      ffi
     redis (4.1.1)
     ruby-fann (1.2.6)
     sinatra (2.0.5)
@@ -43,9 +56,12 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  activemerchant
+  bcrypt
   cassandra-driver
   puma
   rake
+  rbnacl
   redis
   ruby-fann
   sinatra