Mypy checks

Author: stellasia

src/neo4j_graphrag/experimental/components/graph_pruning.py

@@ -69,7 +69,7 @@ def number_of_pruned_relationships(self) -> int:
     def number_of_pruned_properties(self) -> int:
         return len(self.pruned_properties)
 
-    def __str__(self):
+    def __str__(self) -> str:
         return (
             f"PruningStats: nodes: {self.number_of_pruned_nodes}, "
             f"relationships: {self.number_of_pruned_relationships}, "