Bump puma from 3.12.6 to 4.3.12

Bumps [puma](https://github.com/puma/puma) from 3.12.6 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@v3.12.6...v4.3.12)

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

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

Author: dependabot[bot]

Gemfile

@@ -10,7 +10,7 @@ gem 'nokogiri', '1.10.8'
 gem 'will_paginate',           '3.1.6'
 gem 'bootstrap-will_paginate', '1.0.0'
 gem 'bootstrap-sass', '3.4.1'
-gem 'puma',         '3.12.6'
+gem 'puma',         '4.3.12'
 gem 'sass-rails',   '5.0.6'
 gem 'uglifier',     '3.2.0'
 gem 'coffee-rails', '4.2.2'

Gemfile.lock

@@ -319,7 +319,8 @@ GEM
     pry (0.11.3)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
-    puma (3.12.6)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.2.3)
     rack-test (0.8.2)
       rack (>= 1.0, < 3)
@@ -468,7 +469,7 @@ DEPENDENCIES
   nicescroll-rails (~> 3.5, >= 3.5.4.1)
   nokogiri (= 1.10.8)
   pg (= 0.18.4)
-  puma (= 3.12.6)
+  puma (= 4.3.12)
   rails (= 5.1.4)
   rails-controller-testing (= 1.0.2)
   rubocop