const github.com/refraction-networking/utls/dicttls.SigScheme_ecdsa_secp256r1_sha256

one use

	github.com/refraction-networking/utls/dicttls (current package)
		signaturescheme.go#L10: 	SigScheme_ecdsa_secp256r1_sha256            uint16 = 0x0403