Add validation for remote JSON

rails-app/Gemfile

@@ -4,7 +4,7 @@ git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 ruby '2.5.5'
 
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
-gem 'rails', '~> 5.2.2', '>= 5.2.2.1'
+gem 'rails', '~> 6.0.0.rc1'
 # Use postgresql as the database for Active Record
 gem 'pg', '>= 0.18', '< 2.0'
 # Use Puma as the app server