Bump puma from 3.9.1 to 3.12.6

Bumps [puma](https://github.com/puma/puma) from 3.9.1 to 3.12.6.
- [Release notes](https://github.com/puma/puma/releases)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](puma/puma@v3.9.1...v3.12.6)

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile

@@ -7,7 +7,7 @@ git_source(:github) do |repo_name|
 end
 
 gem 'rails',        '5.1.4'
-gem 'puma',         '3.9.1'
+gem 'puma',         '3.12.6'
 gem 'sass-rails',   '5.0.6'
 gem 'uglifier',     '3.2.0'
 gem 'coffee-rails', '4.2.2'

Gemfile.lock

@@ -92,6 +92,7 @@ GEM
       mini_mime (>= 0.1.1)
     method_source (1.0.0)
     mini_mime (1.0.2)
+    mini_portile2 (2.5.0)
     minitest (5.14.4)
     minitest-reporters (1.1.14)
       ansi
@@ -101,6 +102,9 @@ GEM
     multi_json (1.15.0)
     nenv (0.3.0)
     nio4r (2.5.7)
+    nokogiri (1.11.2)
+      mini_portile2 (~> 2.5.0)
+      racc (~> 1.4)
     nokogiri (1.11.2-x86_64-darwin)
       racc (~> 1.4)
     notiffany (0.1.3)
@@ -110,7 +114,7 @@ GEM
     pry (0.14.0)
       coderay (~> 1.1)
       method_source (~> 1.0)
-    puma (3.9.1)
+    puma (3.12.6)
     racc (1.5.2)
     rack (2.2.3)
     rack-test (1.1.0)
@@ -192,6 +196,7 @@ GEM
     websocket-extensions (0.1.5)
 
 PLATFORMS
+  ruby
   x86_64-darwin-20
 
 DEPENDENCIES
@@ -204,7 +209,7 @@ DEPENDENCIES
   listen (= 3.0.8)
   minitest-reporters (= 1.1.14)
   pg (= 1.2.3)
-  puma (= 3.9.1)
+  puma (= 3.12.6)
   rails (= 5.1.4)
   rails-controller-testing (= 1.0.2)
   sass-rails (= 5.0.6)