Update changelog

Author: AdrianSosic

HISTORY.md

@@ -19,6 +19,8 @@ Our backwards-compatibility policy can be found [here](https://github.com/python
   and {func}`cattrs.gen.typeddicts.make_dict_structure_fn` will use the value for the `use_alias` parameter from the given converter by default now.
   If you're using these functions directly, the old behavior can be restored by passing in the desired value directly.
   ([#596](https://github.com/python-attrs/cattrs/issues/596) [#660](https://github.com/python-attrs/cattrs/pull/660))
+- Fix unstructuring of generic classes with stringified annotations 
+  ([#661](https://github.com/python-attrs/cattrs/issues/661) [#662](https://github.com/python-attrs/cattrs/issues/662))
 
 ## 25.1.1 (2025-06-04)