Fix wheel factorization edge case

This fixes the edge case that arises with FACTOR_FINDER method when the wheel factorization level is set lower than the first prime not in the factor base.

Full Changelog: v6.3.0...v6.3.1

sha1sum results:
6c8413163d0bc6afc23337f83370659745cbc654 FindAFactor-6.3.1-cp310-cp310-manylinux_2_35_x86_64.whl
ab1c62ad3f92f5aec9cb6ae6b321154b5c433e6d FindAFactor-6.3.1-cp312-cp312-manylinux_2_39_x86_64.whl
129a71959d41300344992c0a77100aea31f65d47 FindAFactor-6.3.1-cp312-cp312-win_amd64.whl
7b6b15d8cfe7723e2c234eb186e195c1a04de159 FindAFactor-6.3.1-cp313-cp313-macosx_13_0_x86_64.whl
87219c3c9c18ab1e5fed6e5d1b131020e5478007 FindAFactor-6.3.1-cp313-cp313-macosx_14_0_arm64.whl
5fdf1ccee9ddf11e4feff9e4e423758e29d2e5e9 FindAFactor-6.3.1-cp313-cp313-macosx_15_0_arm64.whl
f5219432e4542dcadad6506993f594d17f29b15e FindAFactor-6.3.1-cp38-cp38-manylinux_2_31_x86_64.whl
1a51c712828911fffb5be6aeb06e5ecf94077676 findafactor-6.3.1.tar.gz