Bump puma from 3.12.4 to 3.12.6

Bumps [puma](https://github.com/puma/puma) from 3.12.4 to 3.12.6.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](https://github.com/puma/puma/commits)

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

Gemfile

@@ -8,7 +8,7 @@ gem 'rails', '~> 6.0.2'
 # Use postgresql as the database for Active Record
 gem 'pg', '~> 1.2.3'
 # Use Puma as the app server
-gem 'puma', '~> 3.12.4'
+gem 'puma', '~> 3.12.6'
 
 gem 'acts_as_list', '~> 1.0.1'
 gem 'countries', '~> 3.0.1'

Gemfile.lock

@@ -317,8 +317,8 @@ GEM
     pghero (2.4.2)
       activerecord (>= 5)
     public_suffix (4.0.4)
-    puma (3.12.4)
-    puma (3.12.4-java)
+    puma (3.12.6)
+    puma (3.12.6-java)
     rack (2.2.2)
     rack-attack (6.2.2)
       rack (>= 1.0, < 3)
@@ -550,7 +550,7 @@ DEPENDENCIES
   pg (~> 1.2.3)
   pg_query (~> 1.2.0)
   pghero (~> 2.4.2)
-  puma (~> 3.12.4)
+  puma (~> 3.12.6)
   rack-attack (~> 6.2.2)
   rack-contrib
   rack-cors (~> 1.1.1)