Bump rack from 2.2.2 to 2.2.3

Bumps [rack](https://github.com/rack/rack) from 2.2.2 to 2.2.3.
- [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/v2.2.2...2.2.3)

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

Gemfile.lock

@@ -15,8 +15,6 @@ GEM
     chartkick (3.3.1)
     concurrent-ruby (1.1.6)
     ffi (1.12.2)
-    groupdate (5.0.0)
-      activesupport (>= 5)
     httparty (0.18.0)
       mime-types (~> 3.0)
       multi_xml (>= 0.5.2)
@@ -32,7 +30,7 @@ GEM
     multi_xml (0.6.0)
     mustermann (1.1.1)
       ruby2_keywords (~> 0.0.1)
-    rack (2.2.2)
+    rack (2.2.3)
     rack-protection (2.0.8.1)
       rack
     rake (13.0.1)
@@ -65,7 +63,6 @@ PLATFORMS
 DEPENDENCIES
   activerecord
   chartkick
-  groupdate
   rake
   rerun
   sinatra