fix: incorrect upper bound for `s` in `sign` #174

Job	Run time
Build starknet-ff features	47s
Build starknet-curve features	19s
Build starknet-crypto-codegen features	28s
Build starknet-crypto features	38s
Build starknet-core features	1m 9s
Build starknet-providers features	2m 15s
Build starknet-signers features	53s
Build starknet-accounts features	1m 45s
Build starknet-contract features	1m 20s
Build starknet-macros features	36s
Build starknet features	2m 26s
	12m 36s

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