Convert torch_dtype as str to actual torch data type (i.e. "float…

…16" …to `torch.float16`) (#28208)

* Convert torch_dtype as str to actual torch data type (i.e. "float16" to torch.float16)

* Check if passed torch_dtype is an attribute in torch

* Update src/transformers/pipelines/__init__.py

Check type via isinstance

Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>

---------

Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>

src/transformers/pipelines/__init__.py

@@ -892,6 +892,8 @@ def pipeline(
                 'You cannot use both `pipeline(... torch_dtype=..., model_kwargs={"torch_dtype":...})` as those'
                 " arguments might conflict, use only one.)"
             )
+        if isinstance(torch_dtype, str) and hasattr(torch, torch_dtype):
+            torch_dtype = getattr(torch, torch_dtype)
         model_kwargs["torch_dtype"] = torch_dtype
 
     model_name = model if isinstance(model, str) else None