[Cashtab] Upgrade chronik-client to patck new block msgs

Summary:
T2507

Upgrading chronik-client to 0.8.0, which correctly routes websocket messages for "block found".

Test Plan:
Add a console.log(msg`, msg) to the processChronikWsMsg` function in useWallet.js
npm start
Wait for a block to be found (can monitor ecash.coin.dance for this)
Verify a BlockConnected msg appears in the dev console

Reviewers: #bitcoin_abc, kieran709

Reviewed By: #bitcoin_abc, kieran709

Differential Revision: https://reviews.bitcoinabc.org/D11629