chore: update changelog

Author: gadomski

CHANGELOG.md

@@ -18,6 +18,7 @@
 - `__geo_interface__` for items ([#885](https://github.com/stac-utils/pystac/pull/885))
 - Optional `strategy` parameter to `catalog.add_items()` ([#967](https://github.com/stac-utils/pystac/pull/967))
 - `start_datetime` and `end_datetime` arguments to the `Item` constructor ([#918](https://github.com/stac-utils/pystac/pull/918))
+- `RetryStacIO` ([#986](https://github.com/stac-utils/pystac/pull/986))
 
 ### Removed