function stringifySemverNumber(arr, dotX) {
  if (dotX) {
    return `${arr[0]}.x`;
  }
  return `${arr[0]}.${arr[1]}.${arr[2]}`;
}
Stringify a semver number array
@param {number[]} arr The array to stringify
@param {boolean} dotX If "true", return "5.X" instead of "5.5.5"
@returns