For current cargo-audit v0.20.0, building without --locked resulted in the failure of cargo audit command.

Such buggy cargo-audit build will shows error like:

cargo audit
    Fetching advisory database from `https://github.com/RustSec/advisory-db.git`
error: couldn't fetch advisory database: git operation failed: failed to prepare fetch: An IO error occurred when talking to the server

It caused our CI using this action failed: https://github.com/dfinity/sdk/actions/runs/8391495630/job/22997036128.

There must be some dependency of cargo-audit have new minor/patch release that is broken.

Adding --locked can make sure that all the dependencies are at the versions when cargo-audit release v0.20.0.
This is the common practice to for dealing with bin crate.

With this fix, the CI of my project can pass now: https://github.com/dfinity/sdk/actions/runs/8396775228/job/22998852636