ci(mergify): upgrade configuration to current format (#794) #1441

Job	Run time
actionlint	6s
build with MSRV (1.66.1)	1m 37s
build with default features	31s
build with no_std (ristretto255)	19s
Clippy	32s
build with no_std (ed25519)	20s
Check Rust doc	34s
Rustfmt	7s
build with no_std (p256)	19s
Check if automatically generated code is up to date	18s
build with no_std (secp256k1)	20s
test on beta	2m 28s
build with no_std (secp256k1-tr)	26s
build with no_std (rerandomized)	18s
	8m 15s

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