Gemfile in nanoc-4.7.8 vs Gemfile in nanoc-4.7.9

@@ -57,10 +57,10 @@
   gem 'redcarpet', platforms: %i[ruby mswin]
   gem 'RedCloth', platforms: :ruby
   gem 'rouge'
   gem 'rubypants'
   gem 'sass'
-  gem 'slim'
+  gem 'slim', '~> 3.0'
   gem 'therubyracer', '~> 0.12'
   gem 'typogruby'
   gem 'uglifier'
   gem 'w3c_validators'
   gem 'yuicompressor'