External runtimes no long work in Ruby 3.0 due to [the separation of positional and keyword arguments](https://www.ruby-lang.org/en/news/2019/12/12/separation-of-positional-and-keyword-arguments-in-ruby-3-0/). This is the same problem as #91 but now the deprecation warning of Ruby 2.7 turned into broken code in Ruby 3.0. The existing pull request #95 fixes this bug.