```ruby
MRuby::Gem::Specification.new('mruby-singleton') do |spec|
  spec.license = 'MIT'
  spec.author  = 'ksss <co000ri@gmail.com>'
end
```

Fix test failure on mruby-2.0.0.
user
```ruby
MRuby::Gem::Specification.new('mruby-singleton') do |spec|
  spec.license = 'MIT'
  spec.author  = 'ksss <co000ri@gmail.com>'

  spec.add_test_dependency 'mruby-metaprog', core: 'mruby-metaprog'
end
```
assistant