Function multisig_script 

pub fn multisig_script(keys: &[[u8; 32]], threshold: u32) -> Script

Create a Tapscript multisig script using OP_CHECKSIGADD.

BIP-342 replaces OP_CHECKMULTISIG with OP_CHECKSIGADD:

<key1> OP_CHECKSIG <key2> OP_CHECKSIGADD ... <keyN> OP_CHECKSIGADD <M> OP_NUMEQUALVERIFY