Add support for GPT-5 model

[JINZIXU1018]

Feature description

With the GPT-5 model, users can achieve more accurate and context-aware responses. This would be particularly useful for applications such as:

• Natural language understanding and generation
• Text summarization
• Code generation and debugging

Your Feature

I believe this feature would significantly enhance the capabilities of OpenManus and make it more versatile for various applications.

[github-actions]

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[github-actions]

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