Feature: modify generateQR method to send as data url in a stream

[bitkarrot]

const generateQR = async text => {
// NOTE: sending as form data as data url in a stream does not seem to work with TG api as of this writing.

lnbitsbot-js/lnbits_api.js

Line 168 in 2eb1b48

// If any known solutions, please feel free to make a pull request.