chore: apply `unreachable_pub` lint to crates #537

Job	Run time
minimal-versions / minimal-versions	33s
set-msrv / set-msrv	3s
test (stable)	49s
build (1.85.0, thumbv7em-none-eabi)	1s
test (1.85.0)	1s
build (1.85.0, wasm32-unknown-unknown)	1s
build (stable, thumbv7em-none-eabi)	1s
build (stable, wasm32-unknown-unknown)	50s
	2m 19s

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