Update committee cache to carry PTC

beacon_node/http_api/src/beacon/states.rs

@@ -382,6 +382,7 @@ pub fn get_beacon_state_committees<T: BeaconChainTypes>(
                                         .try_write_for(std::time::Duration::from_secs(1))
                                         .and_then(|mut cache_write| cache_write.get(shuffling_id))
                                         .and_then(|cache_item| cache_item.wait().ok())
+                                        .map(|cached_shuffling| cached_shuffling.committee_cache)
                                 } else {
                                     None
                                 };