docs: update changelog for integrations/anthropic (#2182)

* Update changelog for integrations/anthropic

* Update CHANGELOG.md

---------

Co-authored-by: Amnah199 <13835656+Amnah199@users.noreply.github.com>
Co-authored-by: Amna Mubashar <amnahkhan.ak@gmail.com>

Author: HaystackBot

integrations/anthropic/CHANGELOG.md

@@ -1,12 +1,18 @@
 # Changelog
 
+## [integrations/anthropic-v4.2.1] - 2025-08-11
+
+### 🐛 Bug Fixes
+
+- Add `input_tokens` in `meta["usage"]` of Anthropic messages (#2173)
+
+
 ## [integrations/anthropic-v4.2.0] - 2025-08-07
 
 ### 🐛 Bug Fixes
 
 - Fixed a bug to enable parallel tool calling (#2154)
 
-
 ## [integrations/anthropic-v4.1.0] - 2025-08-05
 
 ### 🚀 Features