Bump puma from 4.2.0 to 4.3.3 in /example_app (#15)

Bumps [puma](https://github.com/puma/puma) from 4.2.0 to 4.3.3.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v4.2.0...v4.3.3)

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

Author: dependabot[bot]

example_app/Gemfile.lock

@@ -118,7 +118,7 @@ GEM
       pry (~> 0.10)
     pry-rails (0.3.9)
       pry (>= 0.10.4)
-    puma (4.2.0)
+    puma (4.3.3)
       nio4r (~> 2.0)
     quantile (0.2.1)
     rack (2.0.8)