Bump puma from 3.11.0 to 3.12.2

Bumps [puma](https://github.com/puma/puma) from 3.11.0 to 3.12.2.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v3.11.0...v3.12.2)

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

Author: dependabot[bot]

Gemfile

@@ -6,7 +6,7 @@ gem 'rails', '5.1.7'
 # Use postgresql as the database for Active Record
 gem 'pg', '~> 0.18'
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 3.12'
 # use Devise Token Auth for token based authentication
 gem 'devise_token_auth'
 gem 'omniauth'

Gemfile.lock

@@ -110,7 +110,7 @@ GEM
     pry-stack_explorer (0.4.9.2)
       binding_of_caller (>= 0.7)
       pry (>= 0.9.11)
-    puma (3.11.0)
+    puma (3.12.2)
     rack (2.0.8)
     rack-attack (5.0.1)
       rack
@@ -223,7 +223,7 @@ DEPENDENCIES
   pry-byebug
   pry-rails
   pry-stack_explorer
-  puma (~> 3.0)
+  puma (~> 3.12)
   rack-attack
   rack-cors
   rails (= 5.1.7)