[flake8-pyi] Fix false negative for PYI046 with unused generic protocols #23252

Job	Run time
Determine changes	7s
cargo fmt	12s
python package	1m 7s
pre-commit	24s
mkdocs	1m 58s
cargo test (linux)	3m 35s
cargo clippy	1m 51s
cargo test (wasm)	1m 11s
cargo fuzz	4m 8s
cargo udeps	1m 50s
cargo test (windows)	4m 29s
test scripts	58s
benchmarks	6m 4s
formatter instabilities and black similarity	0s
test ruff-lsp	21s
ecosystem	8m 22s
	36m 37s

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