fix quote (#670)

Author: wustzdy

src/memos/graph_dbs/polardb.py

@@ -4056,7 +4056,7 @@ def _build_filter_conditions_cypher(
         if filter:
 
             def escape_cypher_string(value: str) -> str:
-                return value.replace("'", "''")
+                return value.replace("'", "\\'")
 
             def build_cypher_filter_condition(condition_dict: dict) -> str:
                 """Build a Cypher WHERE condition for a single filter item."""