fix for MSRV

crates/red_knot_python_semantic/src/types/narrow.rs

@@ -83,7 +83,7 @@ impl<'db> NarrowingConstraintsBuilder<'db> {
         {
             // SAFETY: we should always have a symbol for every Name node.
             let symbol = self.symbols().symbol_id_by_name(id).unwrap();
-            for (op, comparator) in std::iter::zip(ops, comparators) {
+            for (op, comparator) in std::iter::zip(ops.as_ref(), comparators.as_ref()) {
                 let comp_ty = self
                     .inference()
                     .expression_ty(comparator.scoped_ast_id(self.db, self.scope()));