Bump rack from 2.2.4 to 2.2.6.2 in /examples/playbook-rails (#2264)

Bumps [rack](https://github.com/rack/rack) from 2.2.4 to 2.2.6.2.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@2.2.4...v2.2.6.2)

---
updated-dependencies:
- dependency-name: rack
  dependency-type: indirect
...

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

examples/playbook-rails/Gemfile.lock

@@ -151,7 +151,7 @@ GEM
     puma (5.6.5)
       nio4r (~> 2.0)
     racc (1.6.0)
-    rack (2.2.4)
+    rack (2.2.6.2)
     rack-proxy (0.7.4)
       rack
     rack-test (2.0.2)