add missing rspec dep

Author: bastelfreak

puppet-lint-strict_indent-check.gemspec

@@ -21,6 +21,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'rspec', '~> 3.0'
   spec.add_development_dependency 'rspec-its', '~> 1.0'
   spec.add_development_dependency 'rspec-collection_matchers', '~> 1.0'
+  spec.add_development_dependency 'rspec-json_expectations'
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'simplecov'
 end