Log Message:
textproc/ruby-libxml: update to 3.2.0

Update ruby-libxml to 3.2.0.

== 3.2.0 / 2020-05-09 Charlie Savage

* Fix crash when creating an empty DTD
* Modernize tests to use Bundler to load gem
* Add libxml-ruby.rb file so gem loads in expted way.
* Add support for xmlSaveNoEmptyTags.
* Clean up extconf.rb file