/usr/lib/ruby/vendor_ruby/ is in ruby-stamp 0.6.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/stamp/
/usr/lib/ruby/vendor_ruby/stamp/disambiguator.rb
/usr/lib/ruby/vendor_ruby/stamp/version.rb
/usr/lib/ruby/vendor_ruby/stamp/emitters/
/usr/lib/ruby/vendor_ruby/stamp/emitters/string.rb
/usr/lib/ruby/vendor_ruby/stamp/emitters/ambiguous.rb
/usr/lib/ruby/vendor_ruby/stamp/emitters/two_digit.rb
/usr/lib/ruby/vendor_ruby/stamp/emitters/modifiable.rb
/usr/lib/ruby/vendor_ruby/stamp/emitters/composite.rb
/usr/lib/ruby/vendor_ruby/stamp/emitters/delegate.rb
/usr/lib/ruby/vendor_ruby/stamp/emitters/am_pm.rb
/usr/lib/ruby/vendor_ruby/stamp/emitters/ordinal.rb
/usr/lib/ruby/vendor_ruby/stamp/emitters/lookup.rb
/usr/lib/ruby/vendor_ruby/stamp/translator.rb
/usr/lib/ruby/vendor_ruby/stamp.rb