YIP-68: Rotate multisig signers

Summary

Replace the three least active multisig signers with new people. After an open call and careful consideration, we've selected three candidates: 0xngmi, monoloco, and lefteris.

Motivation

The multisig has been effectively operating as 6 of 6-7 with two signers being inactive and another one too busy with his own project. We appreciate their service, but we got to a threshold where we need another rotation. Here are the signing rates over the last two months, since 2022-04-13 till 2022-06-13.

owner
klim       100.0
cp0x        99.0
banteg      98.0
daryl       91.0
mariano     88.0
leo         77.0
--- cut here ---
vsh         39.0
devops       6.0
ryan         2.0

Specification

Replace vsh, devops, ryan with 0xngmi, monoloco, and lefteris.