/usr/lib/ruby/ is in ruby-mime-types 2.6.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/mime/
/usr/lib/ruby/vendor_ruby/mime/types.rb
/usr/lib/ruby/vendor_ruby/mime/type.rb
/usr/lib/ruby/vendor_ruby/mime/type/
/usr/lib/ruby/vendor_ruby/mime/type/columnar.rb
/usr/lib/ruby/vendor_ruby/mime/types/
/usr/lib/ruby/vendor_ruby/mime/types/deprecations.rb
/usr/lib/ruby/vendor_ruby/mime/types/loader.rb
/usr/lib/ruby/vendor_ruby/mime/types/logger.rb
/usr/lib/ruby/vendor_ruby/mime/types/columnar.rb
/usr/lib/ruby/vendor_ruby/mime/types/loader_path.rb
/usr/lib/ruby/vendor_ruby/mime/types/cache.rb
/usr/lib/ruby/vendor_ruby/mime-types.rb