Update Sample App - Knative Function `py` Middleware

[Leo6Leo]

          At some ppint we need to update this.

We are currently rewriting the py middleware, and will likely create also a few new templates.
But that is second half of 2024 - hopefully /cc @lkingland

Originally posted by @matzew in #6007 (comment)

When py middleware is updated, the content in the Bookstore Sample Application need to be updated. Creating the issue to keep track on this.

[github-actions]

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