Beta branch - Not supporting special chars in received payload

[Dancho80]

in case the payload contains some special char like ®, the client fails with error:

TypeError: Cannot convert argument to a ByteString because the character at index 10117 has a value of 8482 which is greater than 255.
at Client.fetch (/smee-client/node_modules/undici/index.js:112:13)
at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
at async Client.onmessage (file:///smee-client/index.js:52:30)