https://github.com/sendbird/sendbird-ios-framework/releases/tag/v3.0.215
• Added the methods below to SBDGroupChannel class.
• createChannelWithParams:progressHandler:completionHandler:
• createDistinctChannelIfNotExistWithParams:progressHandler:completionHandler:
• updateChannelWithParams:progressHandler:completionHandler:
• Fixed bug of requestId in SBDBaseMessage object.
