Bump rack from 2.0.3 to 2.2.3

Bumps [rack](https://github.com/rack/rack) from 2.0.3 to 2.2.3.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/master/CHANGELOG.md)
- [Commits](rack/rack@2.0.3...2.2.3)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Gemfile.lock

@@ -28,7 +28,7 @@ GEM
       hashie (>= 3.4.6, < 3.6.0)
       rack (>= 1.6.2, < 3)
     public_suffix (3.0.1)
-    rack (2.0.3)
+    rack (2.2.3)
     rack-openid (1.4.2)
       rack (>= 1.1.0)
       ruby-openid (>= 2.1.8)