(Old branch) Feature: Pydantic V2 support

[NowanIlfideme]

Trying to add support for Pydantic V2.

Currently, it's impossible, as Pydantic doesn't support cusom encoders for JSON (or any other type). Or at least I couldn't figure out how to add it; it's referenced in docs.

Related issues/discussions in Pydantic:

Main discussion - pydantic/pydantic#4456

Apparently, serialization is already implemented here? - pydantic/pydantic#4739 - but I can't find any documentation, and I can't find it in the Python interface code for pydantic-core.

V1 JSON Encoder issue/discussion - pydantic/pydantic#2277

Closes #15 when merged.

[NowanIlfideme]

JSON/YAML dumping of simple models still work in V2, but not the trickery done for serializing the fields with arbitrary types.

As I understand, V2 will switch to using "field serializers", rather than allowing json_encoders. This might make it easier to apply models with custom types in general, but you'd need to apply how to encode them to each model. Anyways, this will have to wait until it's more clear from Pydantic's side.