Bump puma from 5.2.2 to 5.6.2 in /examples/rails-blog

Bumps [puma](https://github.com/puma/puma) from 5.2.2 to 5.6.2.
- [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/v5.2.2...v5.6.2)

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

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

examples/rails-blog/Gemfile

@@ -8,7 +8,7 @@ gem 'rails', '~> 6.1.1'
 # Use postgresql as the database for Active Record
 gem 'pg', '~> 1.1'
 # Use Puma as the app server
-gem 'puma', '~> 5.0'
+gem 'puma', '~> 5.6'
 # Use SCSS for stylesheets
 gem 'sass-rails', '>= 6'
 # Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker

examples/rails-blog/Gemfile.lock

@@ -100,13 +100,13 @@ GEM
     mini_portile2 (2.5.0)
     minitest (5.14.4)
     msgpack (1.4.2)
-    nio4r (2.5.7)
+    nio4r (2.5.8)
     nokogiri (1.11.3)
       mini_portile2 (~> 2.5.0)
       racc (~> 1.4)
     pg (1.2.3)
     public_suffix (4.0.6)
-    puma (5.2.2)
+    puma (5.6.2)
       nio4r (~> 2.0)
     racc (1.5.2)
     rack (2.2.3)
@@ -208,7 +208,7 @@ DEPENDENCIES
   jbuilder (~> 2.7)
   listen (~> 3.3)
   pg (~> 1.1)
-  puma (~> 5.0)
+  puma (~> 5.6)
   rack-mini-profiler (~> 2.0)
   rails (~> 6.1.1)
   sass-rails (>= 6)