fix: Compatible with special characters in pg full-text search. (#8921)

Co-authored-by: Aurelius Huang <cm.huang@aftership.com>

api/core/rag/datasource/vdb/pgvector/pgvector.py

@@ -166,7 +166,7 @@ class PGVector(BaseVector):
 
         with self._get_cursor() as cur:
             cur.execute(
-                f"""SELECT meta, text, ts_rank(to_tsvector(coalesce(text, '')), to_tsquery(%s)) AS score
+                f"""SELECT meta, text, ts_rank(to_tsvector(coalesce(text, '')), plainto_tsquery(%s)) AS score
                 FROM {self.table_name}
                 WHERE to_tsvector(text) @@ plainto_tsquery(%s)
                 ORDER BY score DESC