Add a new coordinator for zh_CN

[Dumeng]

Add myself as a new translating coordinator for zh_CN

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📚 Documentation preview 📚: https://cpython-devguide--1150.org.readthedocs.build/

[cpython-cla-bot]

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[ezio-melotti]

Is @zhsj still active on the translations?

[Dumeng]

Actually, we have attempted different ways to contact @zhsj in the past months. Unfortunately, we cannot hear any back. So we are not sure about @zhsj 's status.