build(deps): bump rack from 2.0.6 to 2.2.3 in /dashboard

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]

dashboard/Gemfile.lock

@@ -214,7 +214,7 @@ GEM
     public_suffix (3.0.3)
     puma (3.12.0)
     raabro (1.1.6)
-    rack (2.0.6)
+    rack (2.2.3)
     rack-protection (2.0.5)
       rack
     rack-test (1.1.0)