[Security] Bump rack from 2.0.5 to 2.0.6

Bumps [rack](https://github.com/rack/rack) from 2.0.5 to 2.0.6. **This update includes security fixes.**
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/master/CHANGELOG.md)
- [Commits](rack/rack@2.0.5...2.0.6)

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

Gemfile.lock

@@ -228,7 +228,7 @@ GEM
       activerecord
     public_suffix (3.0.3)
     puma (3.12.0)
-    rack (2.0.5)
+    rack (2.0.6)
     rack-accept-default (0.0.2)
       rack
     rack-mini-profiler (1.0.0)