Add support for `pydantic>=2.0`

Hi.

Great tool! I would love to see support for  `pydantic>=2.0`, but `hue2mqtt` currently depends on v1. This is not a big deal, but it does not integrate well with my own workflow and pydantic has some new features.

[pydantic v2 migration guide](https://docs.pydantic.dev/latest/migration/)

Cheers