Adapt to official media type changes in GraphQL over HTTP spec #563
Description
As of graphql/graphql-over-http#215, the GraphQL over HTTP spec decided to change the official media type for GraphQL responses over HTTP. This means that:
- clients are expected to send requests as
"application/json" - servers are expected to reply with
"application/json"or"application/graphql-response+json", with content negotiation
With this issue, we need to deprecate "application/graphql+json" and introduce support for "application/graphql-response+json".