Bump puma from 3.12.1 to 4.3.12

Bumps [puma](https://github.com/puma/puma) from 3.12.1 to 4.3.12.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v3.12.1...v4.3.12)

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

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

Gemfile

@@ -5,7 +5,7 @@ git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
 ruby '2.6.3'
 
-gem 'puma', '~> 3.11'           # Use Puma as the app server
+gem 'puma', '~> 4.3'            # Use Puma as the app server
 gem 'rails', '~> 5.2.3'         # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'sass-rails', '~> 5.0'      # Use SCSS for stylesheets
 gem 'uglifier', '>= 1.3.0'      # Use Uglifier as compressor for JavaScript assets

Gemfile.lock

@@ -188,7 +188,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.3)
-    puma (3.12.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -317,7 +318,7 @@ DEPENDENCIES
   listen (>= 3.0.5, < 3.2)
   pg
   pry (~> 0.12.2)
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 5.2.3)
   rubocop
   sass-rails (~> 5.0)