add importorskip

[dakinggg]

What does this PR do?

Fixes tests that started failing in nightly (and then on this PR too)

What issue(s) does this change relate to?

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[dskhudia]

Any idea why they started failing in nightly?

[bcui19]

Is there a reason why adding the importskip would fix nightly tests?

[dakinggg]

For the transformers one: It is because Mihir hasn't moved the nightly tests to GHA yet, and the lint check in GHA is installing all not dev. So there is currently no check that runs on PRs that install dev target (but the nightly lint check still runs on dev install target).

For the precision/memory test: This test has been super flaky, sometimes failing because it does not meet the memory difference threshold, sometimes failing with UserWarning: Deallocating Tensor that still has live PyObject references. This probably happened because you took out a weak reference to Tensor and didn't call _fix_weakref() after dereferencing it. Subsequent accesses to this tensor via the PyObject will now fail. (Triggered internally at ../torch/csrc/autograd/python_variable.cpp:323.). I interpreted that error as possibly an OOM, so tried reducing the memory intensity. Not certain it will fix it permanently, and might still be flaky.