Replace Linux only 'resource' library with cross-platform 'psutil' library

[nicoell]

I cannot run tests on windows because 'resource' library is not available on windows

ModuleNotFoundError: No module named 'resource',

I replaced the 'resource' library with psutil: https://pypi.org/project/psutil/

Cross-platform lib for process and system monitoring in Python.

[dgtlmoon]

ah nice one, thanks!

[dgtlmoon]

actually to be honest i think it would be best to remove all the memory test stuff from the tests, i never look at it