[AIT-322] Support protocol version bump to v6#10

lawrence-forooghian wants to merge 1 commit intoAIT-324-apply-on-ACKably/ably-cocoa-plugin-support:AIT-324-apply-on-ACKfrom

AIT-322-v6-ProtocolMessageably/ably-cocoa-plugin-support:AIT-322-v6-ProtocolMessageCopy head branch name to clipboard