Bump rack from 3.2.4 to 3.2.5 in /examples/sinatra

Bumps [rack](https://github.com/rack/rack) from 3.2.4 to 3.2.5.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@v3.2.4...v3.2.5)

---
updated-dependencies:
- dependency-name: rack
  dependency-version: 3.2.5
  dependency-type: indirect
...

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Author: dependabot[bot]

examples/sinatra/Gemfile.lock

@@ -10,7 +10,7 @@ GEM
     logger (1.7.0)
     mustermann (3.0.4)
       ruby2_keywords (~> 0.0.1)
-    rack (3.2.4)
+    rack (3.2.5)
     rack-protection (4.2.1)
       base64 (>= 0.1.0)
       logger (>= 1.6.0)