fix: fix test_torch__getitem fixing the empty dim case in tf backend

[Ishticode]

This fixes test_torch___getitem. Passes with 200+ examples tested.
As an example, it fixes the following mismatch of behaviour between native torch and our torch frontend when tensorflow is set.

import torch
x = torch.tensor([])
y = torch.tensor(True)
print(x.__getitem__(y)) # tensor([], size=(1, 0))

import ivy.functional.frontends.torch as tivy
import ivy
ivy.set_backend('tensorflow')
x = tivy.tensor([])
y = tivy.tensor(True)
print("tf backend:", x.__getitem__(y)) # throws error

[github-actions]

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