Bump puma from 5.6.7 to 5.6.8 in /examples/rails_example (#33)

Bumps [puma](https://github.com/puma/puma) from 5.6.7 to 5.6.8.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v5.6.7...v5.6.8)

---
updated-dependencies:
- dependency-name: puma
  dependency-type: direct:production
...

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

examples/rails_example/Gemfile.lock

@@ -162,13 +162,13 @@ GEM
       digest
       net-protocol
       timeout
-    nio4r (2.5.9)
+    nio4r (2.7.0)
     nokogiri (1.16.2-x86_64-darwin)
       racc (~> 1.4)
     nokogiri (1.16.2-x86_64-linux)
       racc (~> 1.4)
     public_suffix (4.0.7)
-    puma (5.6.7)
+    puma (5.6.8)
       nio4r (~> 2.0)
     racc (1.7.3)
     rack (2.2.6.4)