minor fix to triplet preproc

Author: puririshi98

test/llm/test_large_graph_indexer.py

@@ -14,6 +14,7 @@
     TripletLike,
     get_features_for_triplets,
 )
+from torch_geometric.llm.utils.backend_utils import preprocess_triplet
 from torch_geometric.typing import WITH_PT20
 
 # create possible nodes and edges for graph
@@ -35,11 +36,6 @@ def sample_triplets(amount: int = 1) -> List[TripletLike]:
     return trips
 
 
-def preprocess_triplet(triplet: TripletLike) -> TripletLike:
-    h, r, t = triplet
-    return h.lower(), r, t.lower()
-
-
 def test_basic_collate():
     graphs = [sample_triplets(1000) for i in range(2)]