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>

Gemfile

@@ -8,7 +8,7 @@ gem 'rails', '~> 6.1.1'
 # Use postgresql as the database for Active Record
 gem 'pg', '>= 0.18', '< 2.0'
 # Use Puma as the app server
-gem 'puma', '~> 3.12'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5'
 # Transpile app-like JavaScript. Read more: https://github.com/rails/webpacker

Gemfile.lock

@@ -112,7 +112,8 @@ GEM
       mini_portile2 (~> 2.5.0)
       racc (~> 1.4)
     pg (1.2.3)
-    puma (3.12.6)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     racc (1.5.2)
     rack (2.2.3)
     rack-proxy (0.6.5)
@@ -224,7 +225,7 @@ DEPENDENCIES
   jbuilder (~> 2.7)
   listen (>= 3.0.5, < 3.2)
   pg (>= 0.18, < 2.0)
-  puma (~> 3.12)
+  puma (~> 4.3)
   rails (~> 6.1.1)
   rspec-rails (~> 3.8)
   sass-rails (~> 5)