Add support for building [picoruby](https://github.com/picoruby/picoruby), in particular version 3.0.0 which is stable. This will also require adding picoruby to [ruby-versions](https://github.com/postmodern/ruby-versions).
Add support for building picoruby, in particular version 3.0.0 which is stable. This will also require adding picoruby to ruby-versions.