Update changelog with pending changes (#853)

* Update changelog with pending changes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Update CHANGELOG.md

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: mitchh456

CHANGELOG.md

@@ -1,6 +1,13 @@
 # Changelog
 
 ## Pending
+- Fix `rq` instrumentation: use `Job.id` property instead of removed `get_id()` (#851)
+- Support FastMCP 3.x while maintaining 2.x backwards compatibility (#852)
+- Add security warning for RQ pickle serializer (CWE-502) (#843)
+- Add Redis Cluster instrumentation support (#844)
+- Verify Starlette 1.0.0 compatibility (#846)
+- Drop Python 3.8/3.9 support, add 3.13/3.14 classifiers (#847)
+- Verify 401 responses are not tagged as errors (#849)
 
 ## [3.5.3] 2026-02-12
 - Update core agent version to v1.5.1