This is possible since Rust 1.64.0: https://blog.rust-lang.org/2022/09/22/Rust-1.64.0.html#cargo-improvements-workspace-inheritance-and-multi-target-builds
This adds the 'static_assertions' crate as a dependency of 'ruffle_wstr', but this dependency was already present in the dep tree.
This allows removing the gc_arena dependency in ruffle_wstr