update to asciidoctor 2.0.17 (rhbz#2113688, FTBFS)
The 2.0.17 release includes fixes for some tests which fail with ruby
3.1.
It also adds some new tests which require the open-uri-cached gem.
Disable those tests until open-uri-cached is packaged.
Helped-by: Michael J Gruber <mjg@fedoraproject.org>