Bump puma from 3.12.6 to 5.2.2

Bumps [puma](https://github.com/puma/puma) from 3.12.6 to 5.2.2.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v3.12.6...v5.2.2)

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

Gemfile

@@ -5,7 +5,7 @@ ruby '2.6.3'
 
 gem 'rails', '~> 5.2.1'
 gem 'mysql2', '>= 0.4.4', '< 0.6.0'
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 5.2'
 gem 'sass-rails', '~> 5.0'
 gem 'uglifier', '>= 1.3.0'
 gem 'turbolinks', '~> 5'

Gemfile.lock

@@ -134,7 +134,8 @@ GEM
     pry-rails (0.3.9)
       pry (>= 0.10.4)
     public_suffix (4.0.6)
-    puma (3.12.6)
+    puma (5.2.2)
+      nio4r (~> 2.0)
     racc (1.5.2)
     rack (2.2.3)
     rack-test (1.1.0)
@@ -281,7 +282,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   mysql2 (>= 0.4.4, < 0.6.0)
   pry-rails
-  puma (~> 3.12)
+  puma (~> 5.2)
   rails (~> 5.2.1)
   rails-controller-testing
   rspec-rails (~> 4.0.2)