Add import for torch in test.py

[jpsuarezq]

CUDA_VISIBLE_DEVICES=0 python tools/test.py configs/oneformer3d_qs_radius16_qp300_2many.py work_dirs/clean_forestformer/epoch_3000_fix.pth
/opt/conda/lib/python3.10/site-packages/mmdet3d/evaluation/functional/kitti_utils/eval.py:10: NumbaDeprecationWarning: The 'nopython' keyword argument was not supplied to the 'numba.jit' decorator. The implicit default value for this argument is currently False, but it will be changed to True in Numba 0.59.0. See https://numba.readthedocs.io/en/stable/reference/deprecation.html#deprecation-of-object-mode-fall-back-behaviour-when-using-jit for details.
  def get_thresholds(scores: np.ndarray, num_gt, num_sample_pts=41):
Applying spconv checkpoint fix in-memory...
Traceback (most recent call last):
  File "/workspace/ForestFormer3D/tools/test.py", line 175, in <module>
    main()
  File "/workspace/ForestFormer3D/tools/test.py", line 123, in main
    checkpoint = torch.load(args.checkpoint, map_location='cpu')
NameError: name 'torch' is not defined