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

gmp: update to 6.3.0.
https://github.com/void-linux/void-packages/pull/45341

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

It doesn't seem to have any breaking change (see https://gmplib.org/repo/gmp/file/tip/NEWS) but maybe wise to check more. I'm installing it locally (x86_64) and testing with sagemath.

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