Bump puma from 3.11.0 to 4.3.12

Bumps [puma](https://github.com/puma/puma) from 3.11.0 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@v3.11.0...v4.3.12)

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

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

Author: dependabot[bot]

Gemfile

@@ -13,7 +13,7 @@ gem 'rails', '~> 5.1.4'
 # Use sqlite3 as the database for Active Record
 gem 'sqlite3'
 # Use Puma as the app server
-gem 'puma', '~> 3.7'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets

Gemfile.lock

@@ -94,7 +94,8 @@ GEM
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
     public_suffix (3.0.1)
-    puma (3.11.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.3)
     rack-test (0.8.2)
       rack (>= 1.0, < 3)
@@ -179,7 +180,7 @@ DEPENDENCIES
   coffee-rails (~> 4.2)
   jbuilder (~> 2.5)
   mini_magick
-  puma (~> 3.7)
+  puma (~> 4.3)
   rails (~> 5.1.4)
   sass-rails (~> 5.0)
   selenium-webdriver