Use stream for casting if enabled. (Comfy-Org#7833)

Author: comfyanonymous

comfy/model_management.py

@@ -980,6 +980,9 @@ def cast_to(weight, dtype=None, device=None, non_blocking=False, copy=False, str
         if not copy:
             if dtype is None or weight.dtype == dtype:
                 return weight
+        if stream is not None:
+            with stream:
+                return weight.to(dtype=dtype, copy=copy)
         return weight.to(dtype=dtype, copy=copy)
 
     if stream is not None: