Cargo.toml out of date

[rillian]

Description

//brave/third-party/rust/Cargo.toml has gotten out of sync with the code we're building. This was inevitable since we've been maintaining the vendored rust code manually without proper automation. But currently, the cargo command rejects the declared configuration, which while not affecting the build, prevents running rust-oriented tooling which is helpful in review. Cleaning this up should also help with efforts to get gnrt working for us so we do have some automation.

Steps to Reproduce

1. cd brave/third_party/rust
2. cargo check

Actual result:

An error is returned

Expected result:

Should run to completion with no source changes.