Change list_secrets to use async await

[Lucioric2000]

The list_secrets call returns a coroutine that should be awaited, therefore, I am introducing the await instruction, which was absent, to the async secrets getter example.

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Fixes #<issue_number_goes_here> 🦕

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[gemini-code-assist]

Code Review

This pull request updates the asynchronous sample for listing secrets in the Google Cloud Secret Manager by adding the missing await keyword to the list_secrets method call. This ensures the asynchronous request is properly executed within the async function. I have no feedback to provide.

[daniel-sanche]

Hey, thanks for putting this together. Unfortunately, this is generated code, and can't be directly modified here. We actually made this fix in the code generator recently though, so you should see it roll out to the library soon