Bump puma from 3.11.3 to 3.12.0

Bumps [puma](https://github.com/puma/puma) from 3.11.3 to 3.12.0.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v3.11.3...v3.12.0)

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

Gemfile

@@ -18,7 +18,7 @@ gem 'oj'
 gem 'pg', '~> 1.0'
 gem 'pg_query', '>= 0.9.0'
 gem 'pghero'
-gem 'puma', '~> 3.11'
+gem 'puma', '~> 3.12'
 gem 'rack-cors'
 gem 'sass-rails', '~> 5.0'
 gem 'sentry-raven'

Gemfile.lock

@@ -216,7 +216,7 @@ GEM
     pry-state (0.1.10)
       pry (>= 0.9.10, < 0.12.0)
     public_suffix (3.0.2)
-    puma (3.11.3)
+    puma (3.12.0)
     rack (2.0.5)
     rack-cors (1.0.2)
     rack-mini-profiler (0.10.7)
@@ -428,7 +428,7 @@ DEPENDENCIES
   pry-rescue
   pry-stack_explorer
   pry-state
-  puma (~> 3.11)
+  puma (~> 3.12)
   rack-cors
   rack-mini-profiler
   rails (~> 5.1.5)