Address DeprecationWarning from numpy.testing.decorators

[topspinj]

numpy.testing.decorators is deprecated. Getting this warning:

DeprecationWarning: Importing from numpy.testing.decorators is deprecated, import from numpy.testing instead.

This issue can be resolved by replace numpy.testing.decorators with numpy.testing.

[effigies]

Thanks for the report. This was addressed in #705 and will be part of the next release.