Bump mdl from 0.4.0 to 0.5.0

Bumps [mdl](https://github.com/mivok/markdownlint) from 0.4.0 to 0.5.0.
- [Release notes](https://github.com/mivok/markdownlint/releases)
- [Changelog](https://github.com/markdownlint/markdownlint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/mivok/markdownlint/compare/v0.4.0...v0.5.0)

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

Gemfile

@@ -88,7 +88,7 @@ group :development do
   gem 'capistrano-bundler', '~> 1.2', require: false
   gem 'capistrano-rails', '~> 1.3.1', require: false
   gem 'capistrano3-delayed-job', '~> 1.7.3'
-  gem 'mdl', '~> 0.4.0', require: false
+  gem 'mdl', '~> 0.5.0', require: false
   gem 'rubocop', '~> 0.54.0', require: false
   gem 'rubocop-rspec', '~> 1.24.0', require: false
   gem 'rvm1-capistrano3', '~> 1.4.0', require: false

Gemfile.lock

@@ -239,7 +239,7 @@ GEM
     kgio (2.11.1)
     knapsack_pro (0.53.0)
       rake
-    kramdown (1.14.0)
+    kramdown (1.17.0)
     launchy (2.4.3)
       addressable (~> 2.3)
     letter_opener (1.6.0)
@@ -253,7 +253,7 @@ GEM
       nokogiri (>= 1.5.9)
     mail (2.7.0)
       mini_mime (>= 0.1.1)
-    mdl (0.4.0)
+    mdl (0.5.0)
       kramdown (~> 1.12, >= 1.12.0)
       mixlib-cli (~> 1.7, >= 1.7.0)
       mixlib-config (~> 2.2, >= 2.2.1)
@@ -265,7 +265,8 @@ GEM
     mini_portile2 (2.3.0)
     minitest (5.11.3)
     mixlib-cli (1.7.0)
-    mixlib-config (2.2.4)
+    mixlib-config (2.2.13)
+      tomlrb
     multi_json (1.12.2)
     multi_xml (0.6.0)
     multipart-post (2.0.0)
@@ -460,6 +461,7 @@ GEM
     thread_safe (0.3.6)
     tilt (2.0.8)
     tins (1.15.0)
+    tomlrb (1.2.7)
     turbolinks (2.5.3)
       coffee-rails
     turnout (2.4.0)
@@ -541,7 +543,7 @@ DEPENDENCIES
   knapsack_pro (~> 0.53.0)
   launchy (~> 2.4.3)
   letter_opener_web (~> 1.3.2)
-  mdl (~> 0.4.0)
+  mdl (~> 0.5.0)
   newrelic_rpm (~> 4.1.0.333)
   omniauth (~> 1.8.1)
   omniauth-facebook (~> 4.0.0)