pub fn cosign_taproot(
agg_pk: XOnlyPublicKey,
server_pubkey: PublicKey,
expiry_height: BlockHeight,
) -> TaprootSpendInfopub fn cosign_taproot(
agg_pk: XOnlyPublicKey,
server_pubkey: PublicKey,
expiry_height: BlockHeight,
) -> TaprootSpendInfo