Increase rpc_id entropy

index.js

// Our RPC id's are expected to be the same "length"
// generating id's should use Unix epoch timestamp in miliseconds and append 3 random digits
// currently Kotlin SDK has at least 3 more digits than all other SDKs
// yet while Kotlin is the minority, it's preferable to increase integers than decrease them
// this way we can keep backwards-compatibility for Kotlin clients in older releases
// thus we could also increase entropy by also increasing other SDKs to 6 random digits

function payloadId() {
  const date = Date.now() * Math.pow(10, 6);
  const extra = Math.ceil(Math.random() * Math.pow(10, 6));
  return date + extra;
}