ht.unique() returns torch.Tensor if run locally

[ClaudiaComito]

Description
Output of ht.unique(X) is a torch tensor, not a heat tensor, when X.split is None

To Reproduce

>>> X = ht.array([1, 1, 1, 2, 2, 2])
>>> isinstance(X, ht.DNDarray)
True
>>> isinstance(ht.unique(X), ht.DNDarray)
False
>>> isinstance(ht.unique(X), torch.Tensor)
True

Expected behavior

>>> isinstance(ht.unique(X), ht.DNDarray)
True
>>> isinstance(ht.unique(X), torch.Tensor)
False

Additional comments
Tests should catch this.