Enhancement: use cargo-auditable to add metadata to the binary about dependencies

[cjrh]

Now that openssl is vendored following #401, it would be a good idea to inject dependency information into the executable during the build process:

https://github.com/rust-secure-code/cargo-auditable

Tools can scan all the binaries on a system to check specifically for statically-linked binaries that have reported vulnerabilities and dramatically speed up the process of finding, updating, rebuilding, and deploying such assets.