add missing potential_query_instability for keys and values in hashmap

compiler/rustc_trait_selection/src/traits/auto_trait.rs

@@ -513,6 +513,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
         }
 
         while !vid_map.is_empty() {
+            #[allow(rustc::potential_query_instability)]
             let target = *vid_map.keys().next().expect("Keys somehow empty");
             let deps = vid_map.remove(&target).expect("Entry somehow missing");