do not dispose the iterable until wrapper is disposed

e.g. when a python list is passed to ui listbox, it will hold
a reference to the iterator instance. it works when it iterates
the first time but it crashes on later iterations since
the iterator gets disposed on first iteration

src/runtime/CollectionWrappers/IterableWrapper.cs

@@ -7,36 +7,44 @@ namespace Python.Runtime.CollectionWrappers
     internal class IterableWrapper<T> : IEnumerable<T>
     {
         protected readonly PyObject pyObject;
+        PyIter? iterObject;
 
         public IterableWrapper(PyObject pyObj)
         {
             if (pyObj == null)
                 throw new ArgumentNullException();
+
             pyObject = new PyObject(pyObj.Reference);
         }
 
         IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
-
         public IEnumerator<T> GetEnumerator()
         {
-            PyIter iterObject;
             using (Py.GIL())
             {
                 iterObject = PyIter.GetIter(pyObject);
             }
 
-            using var _ = iterObject;
             while (true)
             {
                 using var GIL = Py.GIL();
 
                 if (!iterObject.MoveNext())
                 {
-                    iterObject.Dispose();
                     break;
                 }
+
                 yield return iterObject.Current.As<T>()!;
             }
         }
+
+        ~IterableWrapper()
+        {
+            using (Py.GIL())
+            {
+                iterObject?.Dispose();
+                iterObject = null;
+            }
+        }
     }
 }