Using `@model_validator` with mode='after' on a classmethod is deprecated

[fubuloubu]

Started noticing these warnings in my test runs as of Pydantic 2.12 release:

PydanticDeprecatedSince212: Using @model_validator with mode='after' on a classmethod is deprecated. Instead, use an instance method. See the documentation at https://docs.pydantic.dev/2.12/concepts/validators/#model-after-validator. Deprecated in Pydantic V2.12 to be removed in V3.0.

ape/src/ape/api/networks.py

Line 125 in 6d9ca6b

@model_validator(mode="after")

ape/src/ape_ethereum/transactions.py

Line 148 in 6d9ca6b

@model_validator(mode="after")

[linear]

APE-2021