Fix errors detected by Ruff (#3918)

### What problem does this PR solve?

Fix errors detected by Ruff

### Type of change

- [x] Refactoring

sdk/python/test/test_frontend_api/common.py

@@ -39,7 +39,6 @@ def update_dataset(auth, json_req):
 def upload_file(auth, dataset_id, path):
     authorization = {"Authorization": auth}
     url = f"{HOST_ADDRESS}/v1/document/upload"
-    base_name = os.path.basename(path)
     json_req = {
         "kb_id": dataset_id,
     }