Initialize PyRef marker in native base conversion (#9096)

Fix the missing field in the new into_base initializer without changing its pointer or ownership transfer.

Assisted-by: OpenAI Codex: model identifier unavailable

Co-authored-by: dot <dot@youknowone.org>

crates/vm/src/object/core.rs

@@ -2911,7 +2911,10 @@ where
         // the object's class or MRO since this typed reference was constructed.
         let ptr = self.ptr.cast();
         core::mem::forget(self);
-        PyRef { ptr }
+        PyRef {
+            ptr,
+            marker: PhantomData,
+        }
     }
     #[inline]
     #[must_use]