Bump unicorn from 5.3.0 to 5.4.0

Bumps [unicorn](https://bogomips.org/unicorn/) from 5.3.0 to 5.4.0.

Gemfile

@@ -65,7 +65,7 @@ group :development, :test do
   gem 'simplecov', '~> 0.14.1'
   gem 'rubocop', '0.49.1', require: false
   gem 'rubocop-rspec', '1.15.1'
-  gem 'unicorn', '~> 5.3.0'
+  gem 'unicorn', '~> 5.4.0'
   gem 'rspec_junit_formatter', '~> 0.2.3'
   gem 'poltergeist', '1.15.0'
 end

Gemfile.lock

@@ -188,7 +188,7 @@ GEM
     kaminari (0.15.1)
       actionpack (>= 3.0.0)
       activesupport (>= 3.0.0)
-    kgio (2.11.0)
+    kgio (2.11.2)
     launchy (2.4.3)
       addressable (~> 2.3)
     libv8 (3.16.14.19)
@@ -293,7 +293,7 @@ GEM
       thor (>= 0.18.1, < 2.0)
     rainbow (2.2.2)
       rake
-    raindrops (0.18.0)
+    raindrops (0.19.0)
     rake (12.0.0)
     rdf (1.1.1.1)
     rdf-rdfxml (1.0.1)
@@ -419,7 +419,7 @@ GEM
     unf_ext (0.0.7.1)
     unicode (0.4.4.3)
     unicode-display_width (1.2.1)
-    unicorn (5.3.0)
+    unicorn (5.4.0)
       kgio (~> 2.6)
       raindrops (~> 0.7)
     warden (1.2.6)
@@ -490,7 +490,7 @@ DEPENDENCIES
   therubyracer (~> 0.12.3)
   uglifier (~> 3.2.0)
   unicode (= 0.4.4.3)
-  unicorn (~> 5.3.0)
+  unicorn (~> 5.4.0)
 
 BUNDLED WITH
    1.14.3