title: Embed image doesn't appear discord.js v12
body: <p>I'm trying to collect attachments from a message and then send them in an embed. I've tried this:</p>
  <pre><code>attachment = message.attachments.first()
  url = attachment.url
  
  const embedmem = new Discord.MessageEmbed()
      .setColor('#ffffff')
      .setTitle('Title')
      .setDescription('Description')
      .setImage(url)
  message.channel.send(embedmem);
  </code></pre>
  <p>But no images appeared. Please tell me if I'm doing something wrong.</p>