Fix Rails <= 7.0 builds failing due to change in concurrent-ruby

Author: mshibuya

Appraisals

@@ -2,6 +2,7 @@
 
 appraise 'rails-6.0' do
   gem 'rails', '~> 6.0.0'
+  gem 'concurrent-ruby', '1.3.4' # Workaround for https://github.com/rails/rails/issues/54260
   gem 'psych', '~> 3.3'
   gem 'turbo-rails', '< 2.0.8'
 
@@ -31,6 +32,7 @@ end
 
 appraise 'rails-6.1' do
   gem 'rails', '~> 6.1.0'
+  gem 'concurrent-ruby', '1.3.4' # Workaround for https://github.com/rails/rails/issues/54260
 
   group :active_record do
     platforms :jruby do
@@ -53,6 +55,7 @@ end
 
 appraise 'rails-7.0' do
   gem 'rails', '~> 7.0.0'
+  gem 'concurrent-ruby', '1.3.4' # Workaround for https://github.com/rails/rails/issues/54260
   gem 'importmap-rails', require: false
 
   group :active_record do

gemfiles/rails_6.0.gemfile

@@ -11,6 +11,7 @@ gem "turbo-rails", "< 2.0.8"
 gem "vite_rails", require: false
 gem "webpacker", require: false
 gem "webrick"
+gem "concurrent-ruby", "1.3.4"
 gem "psych", "~> 3.3"
 
 group :development, :test do

gemfiles/rails_6.1.gemfile

@@ -11,6 +11,7 @@ gem "turbo-rails"
 gem "vite_rails", require: false
 gem "webpacker", require: false
 gem "webrick"
+gem "concurrent-ruby", "1.3.4"
 
 group :development, :test do
   gem "pry", ">= 0.9"

gemfiles/rails_7.0.gemfile

@@ -11,6 +11,7 @@ gem "turbo-rails"
 gem "vite_rails", require: false
 gem "webpacker", require: false
 gem "webrick"
+gem "concurrent-ruby", "1.3.4"
 gem "importmap-rails", require: false
 
 group :development, :test do