MNT: Enable cp312 wheels

[effigies]

Also addresses the warning:

In file included from /tmp/build-env-yk9mzha7/lib/python3.12/site-packages/numpy/core/include/numpy/ndarraytypes.h:1929,
                 from /tmp/build-env-yk9mzha7/lib/python3.12/site-packages/numpy/core/include/numpy/ndarrayobject.h:12,
                 from /tmp/build-env-yk9mzha7/lib/python3.12/site-packages/numpy/core/include/numpy/arrayobject.h:5,
                 from indexed_gzip/tests/ctest_zran.c:1215:
/tmp/build-env-yk9mzha7/lib/python3.12/site-packages/numpy/core/include/numpy/npy_1_7_deprecated_api.h:17:2: warning: #warning "Using deprecated NumPy API, disable it with " "#define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION" [-Wcpp]
   17 | #warning "Using deprecated NumPy API, disable it with " \
      |  ^~~~~~~

[pauldmccarthy]

@effigies Thanks, and apologies for the delay!

[effigies]

No worries at all. Thanks for sticking through the Windows CI pain!