webrtc: janus: remove 'audio' and 'video' from publish messages

Those are deprecated and no longer used.

See https://janus.conf.meetecho.com/docs/videoroom and
https://github.com/meetecho/janus-gateway/blob/master/src/plugins/janus_videoroom.c#L9894

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1480>

net/webrtc/src/janusvr_signaller/imp.rs

@@ -96,8 +96,6 @@ struct RoomRequestMsg {
 #[derive(Serialize, Deserialize, Debug, PartialEq, Eq)]
 struct PublishBody {
     request: String,
-    audio: bool,
-    video: bool,
 }
 
 #[derive(Serialize, Deserialize, Debug, PartialEq, Eq)]
@@ -651,8 +649,6 @@ impl Signaller {
             apisecret,
             body: PublishBody {
                 request: "publish".to_string(),
-                audio: true,
-                video: true,
             },
             jsep: Jsep {
                 sdp: sdp_data,