Cross-compile rust binaries

[noseworthy]

We need to compile binaries for multiple platforms. Previously we were doing this by running the build on multiple github runners. Unfortunately github doesn't provide all the platforms we need to build, namely arm64 platforms.

Follow the example from https://github.com/napi-rs/cross-build on how to cross-compile rust binaries using napi-rs to build binaries for windows, mac, and linux for x86 and arm architectures.

• Run only on ubuntu-latest, but specify the rust build target in the matrix and install the required toolchains.
• Need to install xwin for the windows target
• Install zig and use it for linking for macos and linux
• Update to use tiktoken-rs version 0.4.0 which fixes some bugs, but also makes the dependency on async-openai optional which reduces the binary size, but also removes a lot of other dependencies that were complicating the build. tiktoken-node doesn't seem to need any of these dependencies anyway.
• Update version number to 0.0.6

[ceifa]

Wow, this is beautiful! Will take a look at that when get home.

[noseworthy]

Wow, this is beautiful! Will take a look at that when get home.

Thanks! Happy to help (and get my questionable binary out of the repo hahaha) 😄