remove unused dependency (#664)

### What problem does this PR solve?

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/svr/task_executor.py

@@ -89,6 +89,7 @@ def set_progress(task_id, from_page=0, to_page=-1,
     except Exception as e:
         cron_logger.error("set_progress:({}), {}".format(task_id, str(e)))
 
+    close_connection()
     if cancel:
         sys.exit()
 
@@ -312,4 +313,3 @@ if __name__ == "__main__":
 
     while True:
         main()
-        close_connection()

requirements.txt

@@ -50,7 +50,6 @@ joblib==1.3.2
 lxml==5.1.0
 MarkupSafe==2.1.5
 minio==7.2.4
-mpi4py==3.1.5
 mpmath==1.3.0
 multidict==6.0.5
 multiprocess==0.70.16