Add gap for file timestamp update

Author: kthui

qa/L0_model_update/instance_update_test.py

@@ -204,6 +204,7 @@ def test_gpu_cpu_instance_update(self):
         self.__update_instance_count(
             0, 0,
             "{\ncount: 3\nkind: KIND_GPU\n},\n{\ncount: 1\nkind: KIND_CPU\n}")
+        time.sleep(0.1)  # larger the gap for config.pbtxt timestamp to update
         # Remove 1 GPU instance and add 1 CPU instance
         self.__update_instance_count(
             1, 1,