libxcb: migrate to [email protected]

[cho-m]

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[Copilot]

Pull Request Overview

This PR updates the libxcb formula to use Python 3.14 instead of Python 3.13, maintaining consistency with the xcb-proto dependency's Python version requirement.

Key Changes:

• Updated Python dependency from [email protected] to [email protected]
• Updated the Python executable reference from python3.13 to python3.14

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