chore: apply `unreachable_pub` lint to crates #1306

Job	Run time
set-msrv / set-msrv	3s
minimal-versions / minimal-versions	44s
test (1.85.0)	35s
build (1.85.0, thumbv7em-none-eabi)	27s
build (1.85.0, wasm32-unknown-unknown)	25s
build (stable, wasm32-unknown-unknown)	17s
build (stable, thumbv7em-none-eabi)	33s
test (stable)	31s
	3m 35s

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