Update to use new API for deleting a room

[rht]

Currently, the old POST method is used: self.query("post", f"v1/rooms/{room_id}/delete", data=data) (https://github.com/JOJ0/synadm/blob/master/synadm/api.py#L384).

The new route is
DELETE /_synapse/admin/v1/rooms/<room_id>.

See matrix-org/synapse#9889.

[JOJ0]

Hi @rht , thanks a lot for the hint. If you find the time a PR would be welcomed, if not I hope deprecation state will last for a while. I currently try to finally put out a new version with focus on "login as user and related topics" and that's where my "synadm time" currently is spent ;-)

[JOJ0]

Finally fixed this. Thanks for the hint @rht!