my macOS version is 10.15.2 (19C57), i start the command-line tools through the 'USD.command', but when i run usdzconvert, it callTraceback (most recent call last): File "/Applications/usdpython/usdzconvert/usdzconvert", line 17, in <module> usdUtils.printError("failed to import pxr module. Please add path to USD Python bindings to your PYTHONPATH.")NameError: name 'usdUtils' is not defined