fix: allow torch backend split to infer final split size (#28230)

ivy/functional/backends/torch/manipulation.py

@@ -241,6 +241,10 @@ def split(
                 torch.tensor(dim_size) / torch.tensor(num_or_size_splits)
             )
     elif isinstance(num_or_size_splits, list):
+        if num_or_size_splits[-1] == -1:
+            # infer the final size split
+            remaining_size = dim_size - sum(num_or_size_splits[:-1])
+            num_or_size_splits[-1] = remaining_size
         num_or_size_splits = tuple(num_or_size_splits)
     return list(torch.split(x, num_or_size_splits, axis))