I'm trying to setup a community without pict-rs (and as such, without being able to host its pictures myself). I've been tinkering a bit with the API (through python clients, essentially), and I've found how to change my users's avatar to an URL, but not a community. On Lemmy.py, for instance, I have an update() method a community object, but it can't seem to modify anything...
Well, I've finally found a way using plemmy instead of Lemmy.py. Basically :
from plemmy import LemmyHttp
lemmy = LemmyHttp('https://my.lemmy.instance')
lemmy.login('username','password')
lemmy.edit_community(community_id=XXX,banner="http:/yyy.tld/img.jpg")