Fix issue with loading Rails logger in tests

Author: ehelms

spec/dummy/config/boot.rb

@@ -7,4 +7,6 @@
   Bundler.setup
 end
 
-$:.unshift File.expand_path('../../../lib', __dir__)
+$:.unshift File.expand_path('../../../lib', __dir__)
+
+require 'logger' # Fix concurrent-ruby removing logger dependency which Rails itself does not have