fix bad re-zip: use 'w' not 'a'

[mattip]

• I updated the package version in pyproject.toml and made sure the first 3 numbers match ./openblas_commit.txt. If I did not update ./openblas_commit.txt, I incremented the wheel build number (i.e. 0.3.29.0.0 to 0.3.29.0.1)

Note: update ./openblas_commit.txt with cd OpenBLAS; git describe --tags --abbrev=8 > ../openblas_commit.txt

Whoops, bad use of zipfile: 'a' instead of 'w'. While twine caught the problem in upload, I think pip happily accepts the wheel with duplicate libgfortran entries.