OSV-2021-330 Heap-buffer-overflow in bn_sqr_karat_imp

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=30537 Crash type: Heap-buffer-overflow WRITE 8 Crash state: bnsqrkaratimp bnsqrkarat cryptofuzz::module::relicbignum::Sqr::Run...