ci: run cargo-audit
Can be used to detect vulnerabilities in deps, see https://blog.rust-lang.org/inside-rust/2019/10/03/Keeping-secure-with-cargo-audit-0.9.html
Added libssl-dev as it's a build dep of one of audit's crate.
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Can be used to detect vulnerabilities in deps, see https://blog.rust-lang.org/inside-rust/2019/10/03/Keeping-secure-with-cargo-audit-0.9.html
Added libssl-dev as it's a build dep of one of audit's crate.