Avoid treating `dataclasses.KW_ONLY` as typing-only #31828

Job	Run time
cargo fmt	19s
Determine changes	9s
mkdocs	2m 38s
pre-commit	34s
python package	1m 18s
cargo build (msrv)	3m 29s
benchmarks	5m 2s
cargo build (release)	4m 57s
cargo clippy	1m 46s
cargo fuzz	5m 36s
cargo shear	24s
cargo test (linux)	4m 10s
cargo test (windows)	8m 37s
formatter instabilities and black similarity	0s
cargo test (wasm)	1m 36s
test scripts	1m 24s
ecosystem	9m 26s
test ruff-lsp	31s
Fuzz the parser	0s
	51m 56s

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