Bump `aead` dependency to v0.6.0-rc.4 (#752) #1221

Job	Run time
test (x86_64-unknown-linux-gnu, 1.85.0)	26s
build (1.85.0, thumbv7em-none-eabi)	17s
build (stable, wasm32-unknown-unknown)	15s
test (i686-unknown-linux-gnu, stable, sudo apt update && sudo apt install gcc-multilib)	39s
build (1.85.0, wasm32-unknown-unknown)	17s
build (1.85.0, armv7a-none-eabi)	16s
build (stable, thumbv7em-none-eabi)	14s
test (x86_64-unknown-linux-gnu, stable)	25s
test (i686-unknown-linux-gnu, 1.85.0, sudo apt update && sudo apt install gcc-multilib)	44s
build (stable, armv7a-none-eabi)	16s
	3m 49s

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