Dedup gemspec dependencies.

Introduced by 07e0a94 and 828de76.

einhorn.gemspec

@@ -14,14 +14,12 @@ Gem::Specification.new do |gem|
   gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
   gem.name          = 'einhorn'
   gem.require_paths = ['lib']
+
   gem.add_development_dependency 'rake'
-  gem.add_development_dependency 'minitest'
-  gem.add_development_dependency 'mocha'
+  gem.add_development_dependency 'pry'
+  gem.add_development_dependency 'minitest', '< 5.0'
+  gem.add_development_dependency 'mocha', '~> 0.13'
   gem.add_development_dependency 'chalk-rake'
 
-  gem.add_development_dependency('rake')
-  gem.add_development_dependency('pry')
-  gem.add_development_dependency('minitest', '< 5.0')
-  gem.add_development_dependency('mocha', '~> 0.13')
   gem.version       = Einhorn::VERSION
 end