* Fixes checks for serde features in flexbuffers crate
* Removes unused MapReaderIndexer use statement
* Fixes warning about nightly cfg usage
Enabling a cfg attribute through cargo::rustc-cfg in build.rs should be coupled with a cargo::rust-check-cfg value so that the compiler knows about the custom cfg. See: https://doc.rust-lang.org/rustc/check-cfg/cargo-specifics.html#cargorustc-check-cfg-for-buildrsbuild-script.
* Migrates usage of deprecated float constants
This update fixes a compiler warning from use of the old constants.
Constants like EPSILON are now directly on the float primitives (e.g. f32::EPSILON) rather than in the f32 module (std::f32::EPSILON).
The new constants have existed since 1.43.0, which appears to be below the MSRV for the flatbuffers crate.
* Fixes incorrect key in flatbuffers Cargo.toml
The old code was using package.rust, which triggered a warning about an unused key:
warning: flatbuffers/rust/flatbuffers/Cargo.toml: unused manifest key: package.rust
The correct key for specifying MSRV is rust-version. See: https://doc.rust-lang.org/cargo/reference/rust-version.html#rust-version.
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Co-authored-by: Wouter van Oortmerssen <aardappel@gmail.com>