fix: process_device dropping CUDA device index (#1860)

* Fix process_device dropping CUDA device index

* Fix formatting via pre-commit

* Fix formatting via ruff

Author: patelshivani2283-lab

sbi/utils/torchutils.py

@@ -62,9 +62,10 @@ def process_device(device: Union[str, torch.device]) -> str:
                 )
         # Else, check whether the custom device is valid.
         else:
-            check_device(device)
             if isinstance(device, torch.device):
-                device = device.type
+                device = str(device)
+
+            check_device(device)
 
         return device