Fix docs code for ScaleIntensityRangePercentiles

[matt3o]

When running the docs code for ScaleIntensityRangePercentiles, it failed with the error (MONAI 1.2.dev2316):

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/mhadlich/anaconda3/envs/monai/lib/python3.8/site-packages/monai/transforms/intensity/array.py", line 998, in __call__
    img_t = self._normalize(img=img_t)
  File "/home/mhadlich/anaconda3/envs/monai/lib/python3.8/site-packages/monai/transforms/intensity/array.py", line 971, in _normalize
    a_min: float = percentile(img, self.lower)  # type: ignore
  File "/home/mhadlich/anaconda3/envs/monai/lib/python3.8/site-packages/monai/transforms/utils_pytorch_numpy_unification.py", line 121, in percentile
    result = torch.quantile(x, q, dim=dim, keepdim=keepdim)
RuntimeError: quantile() input tensor must be either float or double dtype

This commit updates the docs for the function to use torch.Tensor instead.

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests --disttests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.

[wyli]

/build