Revert to a version of Jekyll that works

Gemfile

@@ -1,6 +1,6 @@
 source 'https://rubygems.org'
 
-gem 'jekyll', '~> 3.7'
+gem 'jekyll', '3.7.4'
 gem 'safe_yaml', '~> 1.0.4'
 gem 'sass', '~> 3.5'
 gem 'libv8', '~> 3.16.14.19'

Gemfile.lock

@@ -18,7 +18,7 @@ GEM
     http_parser.rb (0.6.0)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    jekyll (3.8.4)
+    jekyll (3.7.4)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
@@ -69,7 +69,7 @@ PLATFORMS
 
 DEPENDENCIES
   fontcustom
-  jekyll (~> 3.7)
+  jekyll (= 3.7.4)
   libv8 (~> 3.16.14.19)
   safe_yaml (~> 1.0.4)
   sass (~> 3.5)