async-signature: bump `signature` to v2.3.0-pre.2 #1855

Job	Run time
minimal-versions	21s
build (1.65.0, thumbv7em-none-eabi)	2m 12s
build (1.65.0, wasm32-unknown-unknown)	2m 21s
test (1.65.0)	2m 15s
build (stable, thumbv7em-none-eabi)	12s
test (stable)	12s
build (stable, wasm32-unknown-unknown)	16s
	7m 49s

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