"%zu" to format size_t and "%zi" to format Py_ssize_t not fully supported
VSI C V7.4-001 on OpenVMS IA64 V8.4-2L1,
__CRTL_VER 80500000
Commit bpo-40943: Replace PY_FORMAT_SIZE_T with "z" (GH-20781) use "%zu" to format size_t and "%zi" to format Py_ssize_t.
This generates %CC-W-UNSUPCONVSPEC during compilation, but on few tests, it seem to work.