Avoid `mutable-class-default` violations for Pydantic subclasses #22769

Job	Run time
mkdocs	2m 7s
cargo fmt	14s
Determine changes	7s
pre-commit	46s
python package	1m 10s
benchmarks	6m 16s
cargo fuzz	4m 23s
cargo test (linux)	3m 41s
cargo clippy	1m 50s
cargo test (wasm)	1m 16s
cargo test (windows)	5m 8s
cargo udeps	1m 51s
formatter instabilities and black similarity	0s
test scripts	50s
test ruff-lsp	18s
ecosystem	7m 54s
	37m 51s

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