シグナリング notify の項目を追加する

[zztkm]

• [ADD] SignalingNotify に項目を追加する
  • 追加する項目
    • timestamp
    • spotlightNumber
    • failedConnectionId
    • currentState
    • previousState

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This pull request includes changes to the SignalingNotify struct in the Sora/Signaling.swift file to add new properties and update the Codable conformance. Additionally, the CHANGES.md file has been updated to reflect these changes.

Changes to SignalingNotify struct:

• Added new properties: timestamp, spotlightNumber, failedConnectionId, currentState, and previousState. [1] [2] [3]
• Updated Codable conformance to include the new properties in the CodingKeys enum and the init(from decoder: Decoder) method. [1] [2] [3]

Documentation update:

• Updated CHANGES.md to include the new properties added to SignalingNotify.

[torikizi]

修正ありがとうございます。
動作確認も大丈夫そうでした。