Update irb requirement from 1.13.2 to 1.14.0

Updates the requirements on [irb](https://github.com/ruby/irb) to permit the latest version.
- [Release notes](https://github.com/ruby/irb/releases)
- [Commits](ruby/irb@v1.13.2...v1.14.0)

---
updated-dependencies:
- dependency-name: irb
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile

@@ -16,6 +16,6 @@ group :test do
   gem 'test-unit-ruby-core', '~> 1.0'
   gem 'warning', '~> 1.4.0'
 
-  gem 'irb', '1.13.2'
+  gem 'irb', '1.14.0'
   gem 'power_assert', '2.0.3'
 end