[turbopack]: Update renamed SubpathValue (#49636)
https://github.com/vercel/turbo/pull/4895 renamed `ExportsValue` into
`SubpathValue`
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Co-authored-by: Tobias Koppers <tobias.koppers@googlemail.com>
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>
