_process_picture_url validated the initial picture URL with validate_url()
but then aiohttp followed 3xx redirects without re-validating the target,
so a validate_url-passing public URL could 302 to an internal address and
the body was base64-stored in the user's profile_image_url. This is the
sixth call site of the CVE-2026-45401 redirect-bypass cohort; the other
five already pass allow_redirects=AIOHTTP_CLIENT_ALLOW_REDIRECTS. Apply
the same.