Fix scores assignment.

src/torchmetrics/functional/classification/jaccard.py

@@ -62,7 +62,7 @@ def _jaccard_from_confmat(
 
  # If this class is absent in both target AND pred (union == 0), then use the absent_score for this class.
  scores = intersection.float() / union.float()
- scores.where(union == 0, torch.tensor(absent_score, dtype=scores.dtype, device=scores.device))
+ scores = scores.where(union == 0, torch.tensor(absent_score, dtype=scores.dtype, device=scores.device))
 
  if ignore_index is not None and 0 <= ignore_index < num_classes:
  scores = torch.cat(