Bump up Ferrum

Author: route

cuprite.gemspec

@@ -19,7 +19,7 @@ Gem::Specification.new do |s|
   s.required_ruby_version = ">= 2.3.0"
 
   s.add_runtime_dependency "capybara", ">= 2.1", "< 4"
-  s.add_runtime_dependency "ferrum",   "~> 0.7.0"
+  s.add_runtime_dependency "ferrum",   "~> 0.8.0"
 
   s.add_development_dependency "image_size", "~> 2.0"
   s.add_development_dependency "pdf-reader", "~> 2.1"