Bump puma from 3.4.0 to 5.6.7 in /images/benchmarks/ruby

Bumps [puma](https://github.com/puma/puma) from 3.4.0 to 5.6.7.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](https://github.com/puma/puma/compare/v3.4.0...v5.6.7)

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

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

images/benchmarks/ruby/Gemfile.lock

@@ -2,7 +2,9 @@ GEM
   remote: https://rubygems.org/
   specs:
     mustermann (1.0.3)
-    puma (3.4.0)
+    nio4r (2.5.9)
+    puma (5.6.7)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-protection (2.0.5)
       rack