bp256

Bump `serdect` to v0.3.0-rc.0 #1398

Job	Run time
build (1.73.0, thumbv7em-none-eabi)	30s
test (1.73.0)	34s
build (1.73.0, wasm32-unknown-unknown)	29s
build (stable, thumbv7em-none-eabi)	23s
test (stable)	30s
build (stable, wasm32-unknown-unknown)	25s
doc	43s
	3m 34s

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