ecdsa

Bump `signature` to v2.3.0-pre.0; MSRV 1.71 (#765) #1485

Job	Run time
test (1.73.0)	29s
no_std (thumbv7em-none-eabi, 1.73.0)	1m 59s
test (stable)	29s
no_std (thumbv7em-none-eabi, stable)	2m 1s
no_std (wasm32-unknown-unknown, 1.73.0)	1m 55s
no_std (wasm32-unknown-unknown, stable)	1m 50s
	8m 43s

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