Update the websec-check Rust checklist

[data-sync-user]

Not specific to PushBackend but we should update https://github.com/mozilla-services/websec-check/blob/main/rust.md

Particularly the Recommended crates could use an update (e.g. add tracing along with slog, remove hyper or specify it’s lower level, etc). We could link to our Actix-web Project skeleton but it’s a little out of date currently.

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