sec1: bump `serdect` dependency to v0.3.0-rc.0 #3202

Job	Run time
minimal-versions	0s
build (1.72.0, thumbv7em-none-eabi)	23s
test (1.72.0)	39s
build (1.72.0, wasm32-unknown-unknown)	28s
test (stable)	28s
build (stable, thumbv7em-none-eabi)	21s
build (stable, wasm32-unknown-unknown)	20s
	2m 39s

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