warning: bracket-lib/Cargo.toml: unused manifest key: package.incremental

Has this ever worked before? I mean, it's possible that it changed in newer cargo(s) because it seems it's not a thing under `[package]` but it's:
* in a [profile](https://doc.rust-lang.org/cargo/reference/profiles.html#incremental) section of `Cargo.toml`
* in file [.cargo/config[.toml]](https://doc.rust-lang.org/cargo/reference/config.html#hierarchical-structure) as [`build.incremental`](https://doc.rust-lang.org/cargo/reference/config.html#buildincremental)

Added by commit: https://github.com/amethyst/bracket-lib/commit/c72aabd950054067584bda06cfe474f1d0681de5