der

x509-cert: introduce a `builder::AsyncBuilder` trait #2605

Job	Run time
build (1.65.0, thumbv7em-none-eabi)	3m 9s
build (1.65.0, wasm32-unknown-unknown)	2m 51s
derive (1.65.0)	1m 48s
build (stable, thumbv7em-none-eabi)	1m 28s
derive (stable)	21s
build (stable, wasm32-unknown-unknown)	1m 18s
test (i686-unknown-linux-gnu, ubuntu-latest, 1.65.0, sudo apt update && sudo apt install gcc-mult...	13m 43s
test (i686-unknown-linux-gnu, ubuntu-latest, stable, sudo apt update && sudo apt install gcc-mult...	10m 13s
test (x86_64-unknown-linux-gnu, ubuntu-latest, 1.65.0)	13m 31s
test (x86_64-unknown-linux-gnu, ubuntu-latest, stable)	10m 1s
	58m 23s

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