Change or update NewNodes provider for ZEC

[ahdzib-maya]

According to zcash docs NowNodes provider seems to be using ZMQ which opens the opportunity for an attacker to trick users that use ZEC in xchainjs-lib appllications that run through NewNodes

[Thorian1te]

ZeroMQ Threat Assessment: NOT PRESENT

The xchainjs-zcash package does not implement or use ZeroMQ functionality. The package:

• Uses HTTP-based APIs via Nownodes (zecbook.nownodes.io)
• Relies on @mayaprotocol/zcash-js v1.0.7 for transaction building
• Does not contain any ZMQ, ZeroMQ, or localhost binding code
• Uses external block explorers (Blockchair, zcashexplorer.app)