Fix functorch import

[msaroufim]

CI in main is broken because the file was renamed to functorch_test - this also updates the test. Can't trigger CI signal but would be nice to do so before merge

Run python run_test.py
Fail to import hypothesis in common_utils, tests are not derandomized
Traceback (most recent call last):
  File "/home/runner/work/subclass_zoo/subclass_zoo/run_test.py", line 31, in <module>
    from functorch import FunctorchTest
ImportError: cannot import name 'FunctorchTest' from 'functorch' (/home/runner/.local/lib/python3.[10](https://github.com/albanD/subclass_zoo/actions/runs/8471184919/job/23210593635#step:6:11)/site-packages/functorch/__init__.py)
Error: Process completed with exit code 1.

[msaroufim]

green 🟢