Don't wrap ResourceNotFoundException

If the secret is not on AWS Secrets Manager the client will throw a `ResourceNotFoundException` that will be wrapped in [`SecretCacheObject.__refresh`](https://github.com/aws/aws-secretsmanager-caching-python/blob/8b3ed311982096d6cb6a99ab33299ade3c9811b3/src/aws_secretsmanager_caching/cache/items.py#L97)

I think to **wrap `ResourceNotFoundException` is not good practice**: because after the client application has no way to understand that something is wrong in the configuration of Aws SM, and if you have a hook it will be triggered anyway even if an exception occurred and the value is None.
[the implementation of `SecretCacheHook` will receive `cached_obj = None` in the get method]

从 src/aws_secretsmanager_caching/cache/items.py 中的 SecretCacheObject.__refresh 开始，然后阅读 SecretCacheHook 如何在 get 路径中接收 cached_obj。确认当前对 ResourceNotFoundException 的 wrapping 行为，并将保留该异常定义为完成标准，以便区分配置错误，并且不会使用 None 调用 hook。

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