Require rubygems mfa

pairing_heap.gemspec

@@ -17,24 +17,18 @@ Gem::Specification.new do |spec|
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["source_code_uri"] = spec.homepage
   spec.metadata["documentation_uri"] = "https://rubydoc.info/gems/pairing_heap"
+  spec.metadata["rubygems_mfa_required"] = "true"
+
 
-  # Specify which files should be added to the gem when it is released.
-  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
   spec.files = Dir.chdir(File.expand_path(__dir__)) do
     `git ls-files -z`.split("\x0").reject { |f| f.match(%r{\A(?:test|spec|features)/}) }
   end
   spec.bindir = "exe"
   spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  # Uncomment to register a new dependency of your gem
-  # spec.add_dependency "example-gem", "~> 1.0"
-
   spec.add_development_dependency "minitest", "~> 5.21"
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "simplecov", "~> 0.22.0"
   spec.add_development_dependency "standard", "~> 1.31"
-
-  # For more information and examples about making a new gem, checkout our
-  # guide at: https://bundler.io/guides/creating_gem.html
 end