upgrade to pydantic 2.0

[nbren12]

I've been getting some version conflicts with this.

[nbren12]

Since there are frequent version conflicts with pydantic (since downstream libs often use v2). Ideally we should remove the dependency, and replace the pydantic models with dataclasses.

The main objects using where pydantic methods (parse_obj, parse_raw, parse_) are used are

• earth2mip.schema.EnsembleRun
• earth2mip._config (environment var based config).
  It might be tricky reimplement a general settings object.