ptokens.js v0.15.0

This new release includes:

• pvai-on-eth
• wsb-on-eth
• luxo-on-luxochain
• luxo-on-bsc
• pkeys-on-bsc
• oath-on-eth
• pftm-on-eth
• nuco-on-telos
• ore-on-eth
• pbtc-on-algo
• pusdc-on-algo
• pusdt-on-algo
• pbtc-on-libre
• pusdt-on-libre