textproc/ruby-libxml: update to 4.1.2

4.1.2 (2023-11-04)

* Fix Ruby warnings about undefined allocators (yuuji.yaginuma, Christopher
  Sahnwaldt)
* Fix Schema::Element required? and array? (John Andrews)
* Remove SchemaElement#minOccurs and SchemaElement#maxOccurs since they
  actually did not work (Charlie Savage)
* Fix typo: XPatch -> XPath (Christopher Sahnwaldt)
* Introduce new alternative Homebrew installation search paths to extconf
  makefile (Pierce Brooks)

(taca)