There's a merged pull request on the void-packages repository

python3-Cython: update to 3.0.4.
https://github.com/void-linux/void-packages/pull/46789

Description:
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#### Testing the changes
- I tested the changes in this PR: **briefly**

I tested building numpy & scipy works ok, just to make sure (since 3.0.3 was bad in that respect), so this seems good to go.

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