[ruby/weakref] Use Gemfile instead of Gem::Specification#add_development_dependency.
https://github.com/ruby/weakref/commit/10d547ba12
[ruby/weakref] Use Gemfile instead of Gem::Specification#add_development_dependency.
https://github.com/ruby/weakref/commit/10d547ba12