ruby3.0-dev 3.0.4-7 (amd64 binary) in ubuntu lunar

 Ruby is the interpreted scripting language for quick and easy
 object-oriented programming. It has many features to process text
 files and to do system management tasks (as in perl). It is simple,
 straight-forward, and extensible.
 .
 This package contains the header files and the mkmf library, necessary
 to make extension library for Ruby 3.0. It is also required to build
 many gems.