v3.0.0-rc03

Compared to the previous RC, this version adds a few new convenience API and fixes 3 annoying issues.

💙 Many thanks to @mateuszkwiecinski, @schoeda and @fn-jt for all the feedback 💙

✨ New APIs

• Make ApolloCall.operation public (#3698)
• Add SubscriptionWsProtocolAdapter (#3697)
• Add Operation.composeJsonRequest (#3697)

🪲 Bug fixes

• Allow repeated @fieldPolicy (#3686)
• Fix incorrect merging of nested objects in JSON (#3672)
• Fix duplicate query detection during validation (#3699)