Upgrade dev dependency rake

Author: styd

functionable-json.gemspec

@@ -23,6 +23,6 @@ Gem::Specification.new do |spec|
 
   spec.add_development_dependency 'bundler', '~> 2.0'
   spec.add_development_dependency 'pry', '~> 0.12.2'
-  spec.add_development_dependency 'rake', '~> 10.0'
+  spec.add_development_dependency 'rake', '>= 12.3.3'
   spec.add_development_dependency 'rspec', '~> 3.0'
 end