COMP: Use venv for macOS venv executable

On ARM:

++ basename /Library/Frameworks/Python.framework/Versions/3.9
+ py_mm=3.9
+ VENV=/Users/svc-dashboard/D/P/ITKPythonPackage/scripts/../venvs/3.9
+ VIRTUALENV_EXECUTABLE=/Library/Frameworks/Python.framework/Versions/3.9/bin/virtualenv
+ /Library/Frameworks/Python.framework/Versions/3.9/bin/virtualenv /Users/svc-dashboard/D/P/ITKPythonPackage/scripts/../venvs/3.9
ImportError: cannot import name 'Path' from 'virtualenv.util.path' (/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/virtualenv/util/path/__init__.py)

Author: thewtex

scripts/macpython-build-wheels.sh

@@ -38,7 +38,7 @@ for PYBIN in "${PYBINARIES[@]}"; do
     fi
     py_mm=$(basename ${PYBIN})
     VENV=${SCRIPT_DIR}/../venvs/${py_mm}
-    VIRTUALENV_EXECUTABLE=${PYBIN}/bin/virtualenv
+    VIRTUALENV_EXECUTABLE="${PYBIN}/bin/python3 -m venv"
     ${VIRTUALENV_EXECUTABLE} ${VENV}
     VENVS+=(${VENV})
 done