From GitHub use emilk:
cargo audit output:
Title: Unsound `impl Follow for bool`}}
The fix should be as simple as editing https://github.com/apache/arrow/blob/master/rust/arrow/Cargo.toml from flatbuffers = "0.5.0" to flatbuffers = "0.6.0"
A more longterm improvement is to add a call to cargo audit in your CI to catch these problems as early as possible