`rand` variable unused in `test_resource_tracker`

[saito828koki]

The rand variable is unused in TestResourceTracker.test_resource_tracker. In addition, tempfile is only used for rand, so there's no need to import it.

cpython/Lib/test/_test_multiprocessing.py

Line 5298 in 273a819

rand = tempfile._RandomNameSequence()

[JelleZijlstra]

Thanks for your contribution!