`NameError` due to missing `psutil` import in `bigstream.utility`

[mansouralawi]

While using the bigstream package, I encountered a NameError suggesting that psutil was not defined. This error was raised when invoking the get_number_of_cores function in the utility.py module of the bigstream package.

Error Traceback:
File ".../align/align.py", line 278, in execute_volumetric_alignment_bigstream
affine = affine_align(
File ".../site-packages/bigstream/align.py", line 852, in affine_align
irm = configure_irm(**kwargs)
File ".../site-packages/bigstream/configure_irm.py", line 135, in configure_irm
ncores = ut.get_number_of_cores()
File ".../site-packages/bigstream/utility.py", line 603, in get_number_of_cores
ncores = psutil.cpu_count(logical=False)
NameError: name 'psutil' is not defined

It seems that the psutil module is not imported in the utility.py file, leading to this error.

To resolve this issue, a simple import statement for psutil should be added to the top of the utility.py module.

I'll be creating a PR to address this issue. Let me know if there are any additional details or steps required!

[GFleishman]

Thank you for fixing Mansour! Sorry about the oversight.