Use the universal2 build only on arm64 hardware

osx_utils.sh

@@ -156,7 +156,7 @@ function pyinst_fname_for_version {
     local py_version=$1
     local py_osx_ver=${2:-$(macpython_sdk_for_version $py_version)}
     local inst_ext=$(pyinst_ext_for_version $py_version)
-    if [ "${PLAT:-}" == "arm64" ] || [ "${PLAT:-}" == "universal2" ]; then
+    if [ "$(uname -m)" == "arm64" ]; then
       if [ "$py_version" == "3.9.1" ]; then
         echo "python-${py_version}-macos11.0.${inst_ext}"
       else