@bot.on.message(text=["/скрин <site>"])
async def screen(message: Message, city: Optional[str] = None):
async with aiohttp.ClientSession() as sess:
async with sess.get("http://mini.s-shot.ru/1024x768/1024/png/?" + site.pop) as resp:
result = await message.vk.upload_photo(await resp.read())
await message.answer('Держи', attachment=str(result))
AttributeError: 'str' object has no attribute 'pop'