Modify method call as_str() -> as_ref()

as_str() was removed at commit ab37e45

Author: minoring

vm/src/frame.rs

@@ -802,15 +802,15 @@ impl ExecutingFrame<'_> {
                     let all: Vec<PyStringRef> = vm.extract_elements(&all)?;
                     let all: Vec<String> = all
                         .into_iter()
-                        .map(|name| name.as_str().to_owned())
+                        .map(|name| name.as_ref().to_owned())
                         .collect();
                     Box::new(move |name| all.contains(&name.to_owned()))
                 } else {
                     Box::new(|name| !name.starts_with('_'))
                 };
             for (k, v) in &dict {
                 let k = PyStringRef::try_from_object(vm, k)?;
-                let k = k.as_str();
+                let k = k.as_ref();
                 if filter_pred(k) {
                     self.scope.store_name(&vm, k, v);
                 }