Simplify the usage of dict (#2681)

### What problem does this PR solve?
Simplify the usage of dictionaries

### Type of change

- [x] Refactoring

---------

Co-authored-by: Kevin Hu <[email protected]>

graphrag/entity_resolution.py

@@ -13,7 +13,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 #
-
+import itertools
 import logging
 import re
 import traceback
@@ -93,16 +93,12 @@ def __call__(self, graph: nx.Graph, prompt_variables: dict[str, Any] | None = No
             node_clusters[graph.nodes[node]['entity_type']].append(node)
 
         candidate_resolution = {entity_type: [] for entity_type in entity_types}
-        for node_cluster in node_clusters.items():
+        for k, v in node_clusters.items():
             candidate_resolution_tmp = []
-            for a in node_cluster[1]:
-                for b in node_cluster[1]:
-                    if a == b:
-                        continue
-                    if self.is_similarity(a, b) and (b, a) not in candidate_resolution_tmp:
-                        candidate_resolution_tmp.append((a, b))
-            if candidate_resolution_tmp:
-                candidate_resolution[node_cluster[0]] = candidate_resolution_tmp
+            for a, b in itertools.permutations(v, 2):
+                if self.is_similarity(a, b) and (b, a) not in candidate_resolution_tmp:
+                    candidate_resolution_tmp.append((a, b))
+            candidate_resolution[k] = candidate_resolution_tmp
 
         gen_conf = {"temperature": 0.5}
         resolution_result = set()