Add irb group

Author: p-linnane

Library/Homebrew/Gemfile

@@ -26,6 +26,9 @@ end
 group :formula_test, optional: true do
   gem "minitest", require: false
 end
+group :irb, optional: true do
+  gem "irb", require: false
+end
 group :livecheck, optional: true do
   gem "ruby-progressbar", require: false
 end

Library/Homebrew/dev-cmd/irb.rb

@@ -73,6 +73,7 @@ def run
           Homebrew.install_bundler_gems!(groups: ["pry"])
           require "pry"
         else
+          Homebrew.install_bundler_gems!(groups: ["irb"])
           require "irb"
         end