Fix errors detected by Ruff (#3918)

### What problem does this PR solve?

Fix errors detected by Ruff

### Type of change

- [x] Refactoring

rag/svr/cache_file_svr.py

@@ -33,14 +33,16 @@ def collect():
 
 def main():
     locations = collect()
-    if not locations:return
+    if not locations:
+        return
     logging.info(f"TASKS: {len(locations)}")
     for kb_id, loc in locations:
         try:
             if REDIS_CONN.is_alive():
                 try:
                     key = "{}/{}".format(kb_id, loc)
-                    if REDIS_CONN.exist(key):continue
+                    if REDIS_CONN.exist(key):
+                        continue
                     file_bin = STORAGE_IMPL.get(kb_id, loc)
                     REDIS_CONN.transaction(key, file_bin, 12 * 60)
                     logging.info("CACHE: {}".format(loc))