Bump puma from 4.3.12 to 5.6.9 in /examples/simple_rails_api

Bumps [puma](https://github.com/puma/puma) from 4.3.12 to 5.6.9.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v4.3.12...v5.6.9)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

examples/simple_rails_api/Gemfile

@@ -6,7 +6,7 @@ gem 'rails', '~> 6.0.2'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3', '~> 1.4'
 # Use Puma as the app server
-gem 'puma', '~> 4.3'
+gem 'puma', '~> 5.6'
 # Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
 # gem 'jbuilder', '~> 2.7'
 # Use Redis adapter to run Action Cable in production

examples/simple_rails_api/Gemfile.lock

@@ -82,11 +82,11 @@ GEM
     mini_portile2 (2.8.0)
     minitest (5.14.4)
     msgpack (1.4.2)
-    nio4r (2.5.8)
+    nio4r (2.7.3)
     nokogiri (1.13.4)
       mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
-    puma (4.3.12)
+    puma (5.6.9)
       nio4r (~> 2.0)
     racc (1.6.0)
     rack (2.2.3)
@@ -150,7 +150,7 @@ DEPENDENCIES
   bootsnap (>= 1.4.2)
   byebug
   listen (>= 3.0.5, < 3.2)
-  puma (~> 4.3)
+  puma (~> 5.6)
   rails (~> 6.0.2)
   spring
   spring-watcher-listen (~> 2.0.0)