chore: apply `unreachable_pub` lint to crates #633

Job	Run time
set-msrv / set-msrv	5s
minimal-versions / minimal-versions	35s
build (stable, thumbv7em-none-eabi)	26s
test (1.85.0)	31s
build (1.85.0, wasm32-unknown-unknown)	20s
build (1.85.0, thumbv7em-none-eabi)	26s
test (stable)	21s
build (stable, wasm32-unknown-unknown)	16s
	3m 0s

Provide feedback