Adding v1 / v2 incompatibility warning for nested v1 model

[sydney-runkle]

Contributing to #10314

from pydantic import BaseModel
from pydantic.v1 import BaseModel as BaseModelV1

class V1Model(BaseModelV1):
    ...

class V2Model(BaseModel):
    inner: V1Model

"""
UserWarning: Nesting V1 models inside V2 models is not supported. Please upgrade V1Model to V2.
"""

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[codspeed-hq]

CodSpeed Performance Report

Merging #10431 will not alter performance

_{Comparing incompat-warning (8f9599f) with main (59a3de7)}

Summary

✅ 49 untouched benchmarks

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
pydantic/_internal
_dataclasses.py
_model_construction.py
Project Total

This report was generated by python-coverage-comment-action

[Viicos]

This will warn when doing the following:

from pydantic import TypeAdapter
from pydantic.v1 import BaseModel as BaseModelV1

TypeAdapter(BaseModelV1)

So maybe there's a way to check for the current model stack before warning?

[sydney-runkle]

Hmm, we don't support TypeAdapter with v1 models anyways... so maybe I should just make the warning more broad?

[sydney-runkle]

I've modified the warning accordingly