Remove stray merge conflict marker from CHANGELOG.md

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: romtsn

CHANGELOG.md

@@ -2,7 +2,6 @@
 
 ## Unreleased
 
-<<<<<<< HEAD
 ### Behavioral Changes
 
 - `SentryOkHttpInterceptor::intercept` now throws `IOException`. This is a source-only and Java-only breaking change ([#5654](https://github.com/getsentry/sentry-java/pull/5654))