chore: update changelog

Author: gadomski

CHANGELOG.md

@@ -28,6 +28,7 @@
 - Switch to pytest ([#939](https://github.com/stac-utils/pystac/pull/939))
 - Use `from __future__ import annotations` for type signatures ([#962](https://github.com/stac-utils/pystac/pull/962))
 - Use `TypeVar` for alternate constructors ([#983](https://github.com/stac-utils/pystac/pull/983))
+- Behavior when required fields are missing in `Item.from_dict` ([#994](https://github.com/stac-utils/pystac/pull/994))
 
 ### Fixed