Bump rack from 2.0.3 to 2.2.2

Bumps [rack](https://github.com/rack/rack) from 2.0.3 to 2.2.2.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/master/CHANGELOG.md)
- [Commits](rack/rack@2.0.3...v2.2.2)

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

Gemfile.lock

@@ -64,6 +64,7 @@ GEM
     crass (1.0.3)
     erubi (1.7.0)
     execjs (2.7.0)
+    ffi (1.9.18)
     ffi (1.9.18-x64-mingw32)
     globalid (0.4.1)
       activesupport (>= 4.2.0)
@@ -83,11 +84,13 @@ GEM
     minitest (5.11.3)
     multi_json (1.13.1)
     nio4r (2.2.0)
+    nokogiri (1.8.2)
+      mini_portile2 (~> 2.3.0)
     nokogiri (1.8.2-x64-mingw32)
       mini_portile2 (~> 2.3.0)
     public_suffix (3.0.1)
     puma (3.11.2)
-    rack (2.0.3)
+    rack (2.2.2)
     rack-test (0.8.2)
       rack (>= 1.0, < 3)
     rails (5.1.4)
@@ -139,6 +142,7 @@ GEM
       actionpack (>= 4.0)
       activesupport (>= 4.0)
       sprockets (>= 3.0.0)
+    sqlite3 (1.3.13)
     sqlite3 (1.3.13-x64-mingw32)
     thor (0.20.0)
     thread_safe (0.3.6)
@@ -164,6 +168,7 @@ GEM
       nokogiri (~> 1.8)
 
 PLATFORMS
+  ruby
   x64-mingw32
 
 DEPENDENCIES