Bump rack from 2.0.6 to 2.2.3

Bumps [rack](https://github.com/rack/rack) from 2.0.6 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@2.0.6...2.2.3)

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

Author: dependabot[bot]

Gemfile.lock

@@ -129,7 +129,7 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.3)
-    rack (2.0.6)
+    rack (2.2.3)
     rack-livereload (0.3.16)
       rack
     rake (12.3.2)