Bump puma from 3.12.2 to 4.3.12

Bumps [puma](https://github.com/puma/puma) from 3.12.2 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@v3.12.2...v4.3.12)

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

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

Gemfile

@@ -8,7 +8,7 @@ gem 'bcrypt'
 gem 'bootsnap', '>= 1.1.0', require: false
 gem 'devise'
 gem 'pg', '>= 0.18', '< 2.0'
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 gem 'rails', '~> 5.2.1'
 gem 'uglifier'
 gem 'webpacker', '~> 4.0.7'

Gemfile.lock

@@ -231,7 +231,8 @@ GEM
     pry-rails (0.3.7)
       pry (>= 0.10.4)
     public_suffix (3.0.3)
-    puma (3.12.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.1.2)
     rack-proxy (0.6.5)
       rack
@@ -374,7 +375,7 @@ DEPENDENCIES
   pg (>= 0.18, < 2.0)
   pointless_feedback (~> 4.1.4)
   pry-rails
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 5.2.1)
   rspec-rails (~> 4.0.0)
   selenium-webdriver