serdect: bump `toml` to v0.8 (#1244) #729

Job	Run time
build (1.65.0, thumbv7em-none-eabi)	4m 51s
test (1.65.0)	4m 56s
test (stable)	41s
build (1.65.0, wasm32-unknown-unknown)	4m 55s
build (stable, thumbv7em-none-eabi)	32s
build (stable, wasm32-unknown-unknown)	25s
minimal-versions / minimal-versions	54s
	17m 14s

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