title: getting error in "invert" command discord.py rewrite v1.3.4
body: <p>Here is my code -</p>
  <pre><code>@client.command()
  async def invert(ctx, user: discord.User = None):
      async with aiohttp.ClientSession() as session:
          async with session.get(str(user.avatar_url)) as response:
              image_bytes = await response.read()
  
      img = Image.open(image_bytes)
      await ImageOps.invert(img)
  
      with io.BytesIO() as my_image:
          img.save(my_image,
                   'PNG')
          my_image.seek(0)
          await ctx.send(file=discord.File(fp=my_image,
                                           filename=&quot;image.png&quot;))
  </code></pre>
  <p>And it gives the error -</p>
  <pre><code>Traceback (most recent call last):
    File &quot;C:\Users\k\AppData\Local\Programs\Python\Python36\lib\site-packages\discord\ext\commands\bot.py&quot;, line 892, in invoke
      await ctx.command.invoke(ctx)
    File &quot;C:\Users\k\AppData\Local\Programs\Python\Python36\lib\site-packages\discord\ext\commands\core.py&quot;, line 797, in invoke
      await injected(*ctx.args, **ctx.kwargs)
    File &quot;C:\Users\k\AppData\Local\Programs\Python\Python36\lib\site-packages\discord\ext\commands\core.py&quot;, line 92, in wrapped
      raise CommandInvokeError(exc) from exc
  discord.ext.commands.errors.CommandInvokeError: Command raised an exception: UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc2 in position 6: invalid continuation byte
  </code></pre>
  <p>I have never used PIL before, so any help will appreciated.</p>