This tests that ulab and python3/numpy match on various slice assignments
that preserve the length of the array. slice assignments that change
the length of the array are not tested.
Unlike the case of "load slice", this case of "modify slice" is not
compared to the built in list type, since "modify slice" is only
implemented in micropython for simple (stride=1) slices.
This will build micropython's master branch with ulab support, and
then run the tests in tests/
At this time, there's only one test and it's not very useful.
