chore: apply `unreachable_pub` lint to crates #538

Job	Run time
minimal-versions / minimal-versions	40s
set-msrv / set-msrv	4s
build (stable, wasm32-unknown-unknown)	17s
build (1.85.0, wasm32-unknown-unknown)	23s
build (1.85.0, thumbv7em-none-eabi)	26s
build (stable, thumbv7em-none-eabi)	34s
test (1.85.0)	33s
test (stable)	29s
	3m 26s

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