ruby-irb is a runtime dependency, not just a check one

Description:

Hi, I’m a packager of another ruby gem and recently a build error comes to my attention: https://aur.archlinux.org/packages/ruby-r18n-core#comment-991073

My own package requires the following packages to be present in check_depends:

checkdepends=("ruby-activesupport" "ruby-kramdown" "ruby-pry-byebug"
              "ruby-redcloth" "ruby-rspec" "ruby-simplecov")

But as you can see in the following stacktrace, loading pry-byebug fails because irb is missing:

An error occurred while loading spec_helper. - Did you mean?
                    rspec ./spec/spec_helper.rb

Failure/Error: require 'pry-byebug'

LoadError:
  cannot load such file -- irb
# ./spec/spec_helper.rb:4:in `<top (required)>'
# ------------------
# --- Caused by: ---
# LoadError:
#   cannot load such file -- pry-byebug
#   ./spec/spec_helper.rb:4:in `<top (required)>'
No examples found.

Do you mind moving ruby-irb as runtime dependency instead of just check dependency?