py : fix scalar-tensor conversion [no ci]

Author: ggerganov

convert_hf_to_gguf.py

@@ -291,8 +291,13 @@ def prepare_tensors(self):
                     bid = int(part)
                     break
 
-            for new_name, data in ((n, d.squeeze().numpy()) for n, d in self.modify_tensors(data_torch, name, bid)):
-                data: np.ndarray  # type hint
+            for new_name, data_torch in (self.modify_tensors(data_torch, name, bid)):
+                data = data_torch.squeeze().numpy()
+
+                # if data ends up empty, it means data_torch was a scalar tensor -> restore
+                if len(data.shape) == 0:
+                    data = data_torch.numpy()
+
                 n_dims = len(data.shape)
                 data_qtype: gguf.GGMLQuantizationType | bool = self.tensor_force_quant(name, new_name, bid, n_dims)