Bump `serdect` to v0.3.0-rc.0 #2028

Job	Run time
build (1.73.0, thumbv7em-none-eabi)	41s
build (1.73.0, wasm32-unknown-unknown)	43s
cross (armv7-unknown-linux-gnueabihf, 1.73.0)	1m 39s
build (stable, thumbv7em-none-eabi)	38s
cross (armv7-unknown-linux-gnueabihf, stable)	2m 1s
build (stable, wasm32-unknown-unknown)	31s
cross (aarch64-unknown-linux-gnu, 1.73.0)	1m 26s
cross (aarch64-unknown-linux-gnu, stable)	1m 16s
cross (powerpc-unknown-linux-gnu, 1.73.0)	1m 33s
cross (powerpc-unknown-linux-gnu, stable)	1m 20s
doc	55s
test (i686-unknown-linux-gnu, 1.73.0, sudo apt update && sudo apt install gcc-multilib)	1m 51s
test (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	1m 53s
test (x86_64-unknown-linux-gnu, 1.73.0)	1m 24s
test (x86_64-unknown-linux-gnu, stable)	1m 12s
	19m 3s

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