fix: Add Concurrent Ruby dependency to Rails (#1331)

Author: arielvalentin

instrumentation/rails/lib/opentelemetry/instrumentation/rails.rb

@@ -21,5 +21,6 @@ module Rails
 require 'opentelemetry-instrumentation-action_mailer'
 require 'opentelemetry-instrumentation-active_record'
 require 'opentelemetry-instrumentation-active_job'
+require 'opentelemetry-instrumentation-concurrent_ruby'
 require_relative 'rails/instrumentation'
 require_relative 'rails/version'

instrumentation/rails/opentelemetry-instrumentation-rails.gemspec

@@ -33,6 +33,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'opentelemetry-instrumentation-active_record', '~> 0.8.0'
   spec.add_dependency 'opentelemetry-instrumentation-active_support', '~> 0.7.0'
   spec.add_dependency 'opentelemetry-instrumentation-base', '~> 0.22.1'
+  spec.add_dependency 'opentelemetry-instrumentation-concurrent_ruby', '~> 0.21.4'
 
   spec.add_development_dependency 'appraisal', '~> 2.5'
   spec.add_development_dependency 'bundler', '~> 2.4'