I am trying to put player headshots inside / mask a circle around. However I get a colour on the background rather than transparent.Anyone have any idea how I might achieve this?

Currently this is the code that I have used.

import urllib.request
from PIL import Image, ImageDraw

def crop_image(url):
    img = Image.open(urllib.request.urlopen(f"{url}"))
    
    img = img.convert("RGBA")
    
    # Create a circular mask
    size = (min(img.size),) * 2
    mask = Image.new('L', size, 0)
    draw = ImageDraw.Draw(mask)
    draw.circle((size[0] // 2, size[1] // 2), radius=size[0] // 2, fill="white", outline="grey", width=5)

    # Apply the mask to the image
    img = img.crop((0, 0, size[0], size[1]))
    img.putalpha(mask)
    
    img.save(r"C:UserspeterskDesktopoutput.png")
    
    return img

url = "https://static.www.nfl.com/image/private/t_person_squared_mobile/f_auto/league/icjfdfsncqlsqe49iujv"

crop_image(url)