Fix: possible memory leaks close #5277 (#5500)

### What problem does this PR solve?

close #5277 by make sure the file close

### Type of change

- [x] Performance Improvement

---------

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

rag/svr/task_executor.py

@@ -18,6 +18,7 @@
 # beartype_all(conf=BeartypeConf(violation_type=UserWarning))    # <-- emit warnings from all code
 import random
 import sys
+
 from api.utils.log_utils import initRootLogger, get_project_base_directory
 from graphrag.general.index import WithCommunity, WithResolution, Dealer
 from graphrag.light.graph_extractor import GraphExtractor as LightKGExt