Png with transparency is added twice

Bug Report

Description of the problem

When I try to insert a png with transparency into the document, the image is inserted twice.

this is the image: https://drive.google.com/file/d/1Paci2YPG0PAvnvNgGlVazkn3cL8txICt/view?usp=sharing

this is the output pdf https://drive.google.com/file/d/1O3sRSiHnLCpRkiflb7tjzWfxGh7xbvSf/view?usp=sharing

Code sample

const PDFDocument = require('pdfkit');
const fs = require('fs');

  const doc = new PDFDocument( {
    layout: 'portrait',
    size: 'letter',
    margin: 0,
  });

  doc.image('./google0.026317087946030382.png', 0 ,0 , { width: 150, height: 100});

  const pdfFile = `./output.pdf`;
  doc.pipe(fs.createWriteStream(pdfFile));
  doc.end();  

Your environment

• pdfkit version: ^0.8.3
• Node version: v8.10.0
• Operating System: ubuntu:16.04 and Windows 10

[swftvsn]

we use https://github.com/lovell/sharp to preprocesses image on the fly to produce consistent results across wide variety of images. It handles multiple formats so we can accept images in many formats and produce predictable pdfs without worrying about users supplying webp or other formats.

[blikblum]

Version 0.9 should fix thix