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

python3-gmpy2: patch and rebuild for mpfr-4.2.1
https://github.com/void-linux/void-packages/pull/46192

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

Fixes check as reported in #46170.

This is an actual bug (or two) already fixed upstream. See https://github.com/aleaxit/gmpy/issues/418, fixed by https://github.com/aleaxit/gmpy/pull/422/commits/68a6b489c3d8d95b2658a1ed884fb99f4bd955c1 and https://github.com/aleaxit/gmpy/commit/7351e2eb1abf4b37a47a822eb3f3f29f90c7f854.

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