Fixing Rust Dependencies Vulnerabilities

Just because I don't see it mentioned anywhere in the post - this can be done locally using cargo-audit [1] [2]. Cargo-audit also has a recommended setup for Travis CI [3]

[1] https://github.com/rustsec/cargo-audit [2] https://crates.io/crates/cargo-audit [3] https://github.com/RustSec/cargo-audit#using-cargo-audit-on-...