Use animated webp instead of gif for animated assets - #10492

1. Your diff is disproportionate to the change because you forgot to maintain the magic trailing comma.
2. I think this might be potentially too much of a breaking change. Last time I changed the default format people were complaining about a bunch of things because they'd be feeding this into image libraries like PIL which do not support webp. Since I changed the default from PNG to WEBP last time for images, people did get into the habit of specifying a format for consumption afterwards but I'm not sure they did for animated images so something to keep in mind.

1. Your diff is disproportionate to the change because you forgot to maintain the magic trailing comma.
2. I think this might be potentially too much of a breaking change. Last time I changed the default format people were complaining about a bunch of things because they'd be feeding this into image libraries like PIL which do not support webp. Since I changed the default from PNG to WEBP last time for images, people did get into the habit of specifying a format for consumption afterwards but I'm not sure they did for animated images so something to keep in mind.

1. Fixed!
2. I don't really do image manipulation, but it seems to be supported now and works fine if saved as a gif (i think people do that anyways?):

Docs: https://pillow.readthedocs.io/en/stable/handbook/image-file-formats.html#webp
Test:

import os

import requests
from PIL import Image

url = 'https://cdn.discordapp.com/avatars/59152242862723072/a_ddde070fdf76e2ed5c8f2645959ab5c2.webp?size=1024&animated=true' # thanks ste🅱️e

res = requests.get(url, stream=True)
image = Image.open(res.raw)

image.save('test.gif', save_all=True)
os.startfile('test.gif')

Regardless of that, assets uploaded as animated webp require the use of this format, .gif points to an unknown resource.