feat(base): Response::delta_token has been removed from Simplified MSC3575.

This patch removes the `Response::delta_token` field from Simplified
MSC3575 (it's a living spec).

Author: Hywan

Cargo.lock

@@ -281,7 +281,6 @@ pub mod simplified_msc3575 {
             s.lists = From::from(value.lists);
             s.rooms = From::from(value.rooms);
             s.extensions = From::from(value.extensions);
-            s.delta_token = value.delta_token;
 
             s
         }