bump allocator with Sync and lock-free

[liuq19]

No description provided.

[eloff]

I have a lock-free arena allocator for Rust, it uses mmap/VirtualAlloc directly, but it wouldn't be hard to modify it to use std::alloc instead. I'd be happy to contribute that code if it interests you (you can use it as a guide if nothing else.)

[liuq19]

Thanks a lot, that is interesting, the allocator is open-source? could you share the crate?

But, the code is changing and we will not need it sonic-rs 0.4.