Fcm gem not working for ruby 1.9.3, Any alternative to implement fcm based push notifications

Currently we are using "gcm" gem to send push notifications from rails server to android and ios apps. Now we need to update gcm to fcm. When I tried to use "fcm" gem getting error "required ruby version above 2.0.0" while bundle install. can any one please help me any alternate solution to implement fcm based push notifications in ruby on rails. Our project ruby version 1.9.3 and rails 3.2.10.

Thanks in advance...