RailsApps mysql2 gem version error with Rails 5.2.1

Question

I am facing a mysql2 gem version error while trying to create a new RailsApps example application using Rails Composer. For example, while creating a rails-devise-roles example with the following command:

$ rails new rails-devise-roles -m https://raw.github.com/RailsApps/rails-composer/master/composer.rb

The error is:

Error loading the 'mysql2' Active Record adapter. Missing a gem it depends on? can't activate mysql2 (< 0.6.0, >= 0.4.4), already activated mysql2-0.3.21. Make sure all dependencies are added to Gemfile. (Gem::LoadError)

The messages on the console indicate mysql2 version 0.3.21 is pulled in

run bundle install --without production from "."
Fetching gem metadata from https://rubygems.org/.........
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies....
...................
Using mysql2 0.3.21

The generated Gemfile has

gem 'mysql2', '~> 0.3.18'

I am using ruby 2.5.3 and Rails 5.2.1