error, colon missing,  convert the [:,t,:] syntax of python language into C#


url: https://github.com/yuqinie98/PatchTST/blob/main/PatchTST_supervised/exp/exp_main.py#L142

src code
``` py
      dec_inp = torch.zeros_like(batch_y[:, -self.args.pred_len:, :]).float()
```

csharp code
```
     dec_inp = torch.zeros_like(batch_y[":",-this.args.pred_len,":"]).@float();
```
