Changed the applicability

Author: botahamec

clippy_lints/src/unused_box.rs

@@ -71,7 +71,8 @@ impl LateLintPass<'_> for UnusedBox {
                 format!("function returns `Box<{0}>` when `{0}` implements `Sized`", boxed_ty).as_str(),
                 "change the return type to",
                 boxed_ty.to_string(),
-                Applicability::MaybeIncorrect,
+                // the return value also needs to be changed, so this can't be MachineApplicable
+                Applicability::HasPlaceholders,
             );
         }
     }