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

@@ -6,7 +6,7 @@ gem 'rails', '~> 6.1.3'
 # Use postgresql as the database for Active Record
 gem 'pg'
 # Use Puma as the app server
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '~> 5.0'
 # Use Uglifier as compressor for JavaScript assets

Gemfile.lock

@@ -172,7 +172,8 @@ GEM
     orm_adapter (0.5.0)
     pg (1.2.3)
     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-test (1.1.0)
@@ -338,7 +339,7 @@ DEPENDENCIES
   less-rails (~> 3.0.0)
   letter_opener
   pg
-  puma (~> 3.11)
+  puma (~> 4.3)
   rails (~> 6.1.3)
   rails-controller-testing
   rspec-rails (~> 4.0.1)