Switch to statically analyzed Ruby Guess

[blast-hardcheese]

Ruby guess is broken:

$ upm guess
--> ruby -e '<secret sauce>'
<internal:/nix/store/d3mglw6m4ikwf7aw0rxz3abj5cv176ha-ruby-3.1.4/lib/ruby/3.1.0/rubygems/core_ext/kernel_require.rb>:85:in `require': cannot load such file -- parser/current (LoadError)
    from <internal:/nix/store/d3mglw6m4ikwf7aw0rxz3abj5cv176ha-ruby-3.1.4/lib/ruby/3.1.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
    from -e:1:in `<main>'
exit status 1