Bump rhai_codegen version to require 0.20.3 of rhai.
[package]
name = "rhai_codegen"
-version = "0.4.0"
+version = "0.4.1"
edition = "2018"
authors = ["jhwgh1968", "Stephen Chung"]
description = "Procedural macros support package for Rhai, a scripting language and engine for Rust"
