Use extended_json_encoder when dumping message contents everywhere

Author: MHHukiewitz

src/aleph/sdk/client/authenticated_http.py

@@ -260,7 +260,7 @@ async def _broadcast(
 
         async with self.http_session.post(
             url,
-            json={"sync": sync, "message": message_dict},
+            json={"sync": sync, "message": json.dumps(message_dict, default=extended_json_encoder)},
         ) as response:
             # The endpoint may be unavailable on this node, try the deprecated version.
             if response.status in (404, 405):