chore: update CHANGELOG for @ai-sdk/anthropic upgrade

Co-authored-by: Brendan Kellam <brendan-kellam@users.noreply.github.com>

Author: github-actions[bot]

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 - Upgraded Vercel AI SDK from v5 to v6. [#969](https://github.com/sourcebot-dev/sourcebot/pull/969)
+- Added support for using bearer tokens with anthropic. [#967](https://github.com/sourcebot-dev/sourcebot/pull/967)
 
 ## [4.13.1] - 2026-02-28