chore: apply `unreachable_pub` lint to crates #1307

Job	Run time
minimal-versions / minimal-versions	55s
set-msrv / set-msrv	3s
test (1.85.0)	38s
build (1.85.0, thumbv7em-none-eabi)	26s
build (stable, thumbv7em-none-eabi)	29s
build (stable, wasm32-unknown-unknown)	23s
build (1.85.0, wasm32-unknown-unknown)	21s
test (stable)	37s
	3m 52s

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