URL 構造体が TURN URI に対応していないのに、URL に変換していたのを修正する

[zztkm]

変更内容

• [FIX] URL 構造体が TURN URI に対応していないのに、URL に変換していたのを修正する
  • 意図しないエスケープが発生しないようにした

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This pull request makes several changes to the Sora/ICEServerInfo.swift file to address an issue with handling TURN URIs and updates the CHANGES.md file accordingly. The most important changes include modifying the urls property to handle TURN URIs as strings, updating the initialization and decoding methods, and fixing an issue with URL conversion.

Handling TURN URIs:

• Sora/ICEServerInfo.swift: Changed the urls property from [URL] to [String] to handle TURN URIs as plain strings.
• Sora/ICEServerInfo.swift: Updated the RTCIceServer initialization to use the urls directly as strings.
• Sora/ICEServerInfo.swift: Modified the initializer to accept urls as [String] instead of [URL].
• Sora/ICEServerInfo.swift: Updated the Codable conformance to decode urls as [String].

Documentation:

• CHANGES.md: Added an entry to document the fix for handling TURN URIs and preventing unintended URL escaping.