signatureNormalize: relax check on signature size

Checking that the sig size is >= 64 is enough, this is just a quick check before the actual library method is called.

src/nativeMain/kotlin/fr/acinq/secp256k1/Secp256k1Native.kt

@@ -79,7 +79,7 @@ public object Secp256k1Native : Secp256k1 {
     }
 
     public override fun signatureNormalize(sig: ByteArray): Pair<ByteArray, Boolean> {
-        require(sig.size == 64 || sig.size in 70..73)
+        require(sig.size >= 64){ "invalid signature ${Hex.encode(sig)}" }
         memScoped {
             val nSig = allocSignature(sig)
             val isHighS = secp256k1_ecdsa_signature_normalize(ctx, nSig.ptr, nSig.ptr)