textproc/ruby-asciidoctor: update to 2.0.18

2.0.18 (2022-10-15)

Improvements

* Propagate :to_dir option to document of AsciiDoc table cell (#4297)
* Force encoding of attribute data passed via CLI to UTF-8 if transcoding
  fails (#4351) (@zkaip)
* Add include role to link macro that replaces include directive when
  include is not enabled

Bug Fixes

* Change internal uriish? helper to only detect a URI pattern at start of a
  string; avoids misleading messages (#4357)

* Prevent highlight.js warning when no language is set on source block;
  don't call highlightBlock if data-lang attribute is absent (#4263)

* Don't raise error if Asciidoctor::Extensions.unregister is called before
  groups are initialized (#4270)

* If path is included both partially and fully, store it with true value
  (included fully) in includes table of document catalog
* Reset registry if activate is called on it again (#4256)
* Format source location in exception message when extension code is malformed

* Fix lineno on reader when skip-front-matter attribute is set but end of
  front matter is not found

* Fix Asciidoctor::Cli::Invoker constructor when first argument is a hash

* Update default stylesheet to honor marker on unordered list when marker is
  defined on ancestor unordered list (#4361)

(taca)