Bump rack from 2.2.12 to 2.2.13 in /examples/stacks/rails/blog

Bumps [rack](https://github.com/rack/rack) from 2.2.12 to 2.2.13.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@v2.2.12...v2.2.13)

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

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

Author: dependabot[bot]

examples/stacks/rails/blog/Gemfile.lock

@@ -141,7 +141,7 @@ GEM
     puma (5.6.9)
       nio4r (~> 2.0)
     racc (1.8.1)
-    rack (2.2.12)
+    rack (2.2.13)
     rack-test (2.1.0)
       rack (>= 1.3)
     rails (7.0.8.7)