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] <[email protected]>

Author: dependabot[bot]

Gemfile

@@ -8,7 +8,7 @@ ruby '2.5.3'
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
 gem 'rails', '~> 5.2.1'
 # Use Puma as the app server
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
  gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets

Gemfile.lock

@@ -243,7 +243,8 @@ GEM
       pry (>= 0.10.4)
     psych (3.0.3)
     public_suffix (4.0.6)
-    puma (3.12.6)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     racc (1.5.2)
     rack (2.2.3)
     rack-cors (1.0.5)
@@ -409,7 +410,7 @@ DEPENDENCIES
   pg (>= 0.20.0)
   pry-byebug
   pry-rails
-  puma (~> 3.12)
+  puma (~> 4.3)
   rack-cors (>= 1.0.2)
   rails (~> 5.2.1)
   rails-controller-testing