fix: add duplex to fetches with body

[hansottowirtz]

To be spec compliant fetch actually needs a duplex option when sending a stream as body.

See https://github.com/nodejs/node/issues/46221

This will make this library work in Node.js with native fetch.

[changeset-bot[bot]]

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Latest commit: 5481f6c62120b99b302cd1f032351287c5097518

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