Bump puma from 6.5.0 to 7.2.1 in /demo

Bumps [puma](https://github.com/puma/puma) from 6.5.0 to 7.2.1.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/main/History.md)
- [Commits](puma/puma@v6.5.0...v7.2.1)

---
updated-dependencies:
- dependency-name: puma
  dependency-version: 7.2.1
  dependency-type: direct:production
...

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

Author: dependabot[bot]

demo/Gemfile.lock

@@ -26,12 +26,12 @@ GEM
     listen (3.9.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
-    nio4r (2.7.4)
+    nio4r (2.7.5)
     parallel (1.26.3)
     parser (3.3.6.0)
       ast (~> 2.4.1)
       racc
-    puma (6.5.0)
+    puma (7.2.1)
       nio4r (~> 2.0)
     racc (1.8.1)
     rack (3.1.21)