Update changelog

Author: joepio

CHANGELOG.md

@@ -13,6 +13,7 @@ See [STATUS.md](server/STATUS.md) to learn more about which features will remain
 - Fix Post endpoints not including search params in returned `@id` field.
 - Rebuilding indexes done on separate thread, only once #616 #615
 - Don't require building index for populate commands
+- Refactor `for_agent` arguments to use the new `ForAgent` enum #623
 
 ## [v0.34.2] - 2023-03-04