Remove workflow schedule as it causes the workflow to be disabled in …

…forks

Fix ruby-builder.js - Windows io.mkdirP("D:\\")

Add JRuby 9.2.19.0

Enable sassc test on JRuby on Windows

9.2.18.0 has been released, so this should work now.

Add 2.0.0 on Windows too

Mention Ruby 2.0 in README and add it to CI

document cache-version

Update URLs for RubyInstaller 1 and DevKit

* See ruby#171
  and oneclick/rubyinstaller#400

Add TruffleRuby 21.1.0

Add reminder to use ruby/setup-ruby@v1 for latest Ruby releases