Fix Subscriptions::Serialize incorrectly parsing time zone:
Fix Subscriptions::Serialize incorrectly parsing time zone:

https://user-images.githubusercontent.com/12410942/138542667-c0f0af79-a4c7-479b-b213-6323b9ba9596.png

rmosolgo/graphql-ruby,nevesenin/graphql-ruby,nevesenin/graphql-ruby,rmosolgo/graphql-ruby,rmosolgo/graphql-ruby,nevesenin/graphql-ruby,rmosolgo/graphql-ruby,nevesenin/graphql-ruby