Ruby 2.1.10 and 2.1.9 are apparently the same version
Ruby 2.1.10 and 2.1.9 are apparently the same version

See https://github.com/ruby/setup-ruby/issues/70#issuecomment-659575137
(links to https://github.com/ruby/ruby/compare/v2_1_9...v2_1_10)

setup-ruby only have 2.1.9, not 2.1.10

dentarg/dyno_metadata