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

[cclauss]

This Pydantic warning is raised during our pytest runs on GitHub Actions CI.

parasect/src/parasect/_helpers.py

Lines 290 to 292 in 3e0ef1e

	@model_validator(mode="after")
	@classmethod
	def _check_entries(cls, values): # noqa: B902

.nox/tests-3-11/lib/python3.11/site-packages/parasect/_helpers.py:290
  /Users/runner/work/parasect/parasect/.nox/tests-3-11/lib/python3.11/site-packages/parasect/_helpers.py:290:
    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.
      @model_validator(mode="after")