This is a major release with several large changes:
- Moved MessagePack support to the `msgspec.msgpack` submodule
- New JSON support available in `msgspec.json`
- Improved error message generation to provide full path to the mistyped values
- Renamed the `immutable` kwarg in `msgspec.Struct` to `frozen` to better match python conventions
- Renamed `EncodingError` to `EncodeError`/`DecodingError` to `DecodeError` to better match python conventions
- Improved `pyright` support, allowing more errors to be statically caught by their type checker
- Adds support for Python 3.10 pattern matching on `msgspec.Struct` types
- Adds support for decoding into `typing.Union` types (with a few restrictions)
- General performance improvements across all encoders/decoders