Switch call from removed is_hidden method to hidden property

`ForeignObjectRel.is_hidden()` was removed in
django/django#17862 in favor of the `hidden`
property of the same class. This change will be released in django 5.1.
In previous versions of django, the `hidden` property called the
`is_hidden()` method, so there should not be changes in behavior for
older versions.

reversion/admin.py

@@ -116,7 +116,7 @@ def _reversion_introspect_inline_admin(self, inline):
                     ):
                         fk_name = field.name
                         break
-            if fk_name and not inline_model._meta.get_field(fk_name).remote_field.is_hidden():
+            if fk_name and not inline_model._meta.get_field(fk_name).remote_field.hidden:
                 field = inline_model._meta.get_field(fk_name)
                 accessor = field.remote_field.get_accessor_name()
                 follow_field = accessor