https://discuss.asciidoctor.org/asciidoctor-and-pygments-not-working-under-cygwin64-tp5212p7450.html
To be honest, I'm not that familiar with the cygwin environment, so I'm not really sure what to tell you. We do test Asciidoctor and Pygments together on Windows for each commit. So I know that combination works fine.
> But if I now try to install pygments.rb 0.6.3, it says there is no pygments.rb of that version anywhere.
> The last code commit I see in pygments.rb on Github is end 2017, so it looks unmaintained.
GitHub itself no longer uses Pygments for source highlighting, and since they originally started the Ruby bindings (pygments.rb), I don't expect that project is really going to go anywhere. Rouge stepped in as its replacement and has since become the recommended syntax highlighter in Ruby. It receives quite a bit of activity, esp over the past year.
https://github.com/rouge-ruby/rouge
> I used pygments.rb with asciidoctor because I
wrote a couple of modes for it for a couple of syntaxes we use in our
standards, so moving to another syntax processor isn't that desirable
(although if we get desperate...).
You're free to continue to use pygments.rb, whether it's 0.6.3 or 1.2.1. But we can't control what happens with the syntax highlighter libraries. They are going to change, and that sometimes means making a migration. Although there should be no immediate need, I would recommend starting to explore the switch from Pygments to Rouge.
Best,
-Dan