Gemfile in csl-1.5.2 vs Gemfile in csl-1.6.0

@@ -22,10 +22,9 @@
   gem 'yard', platforms: :mri
   gem 'redcarpet', platforms: :mri
 end
 
 group :coverage do
-  gem 'coveralls', require: false if ENV['CI']
   gem 'simplecov', require: false
 end
 
 # vim: syntax=ruby