Use `aws-actions/setup-sam` to set up

The sample provides a bit dated code. I think using `aws-actions/setup-sam@v2` would remove some boilerplate, and `actions/checkout@v2` is also a bit dated - should be `v4` at this point.

Using `setup-sam` would also imply having a `samconfig.toml` in the root.

首先阅读仓库的 GitHub Actions workflow 以及示例使用的部署配置。更新 workflow，使其使用 aws-actions/setup-sam@v2 和 actions/checkout@v4，添加所请求的根级 samconfig.toml，并验证 continuous delivery 示例仍然有效。

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