chore: Add PR number to CHANGELOG entry

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: antonis

CHANGELOG.md

@@ -10,7 +10,7 @@
 
 ### Fixes
 
-- Attach the on-error Session Replay buffer to feedback submitted from the feedback form ([#XXXX](https://github.com/getsentry/sentry-react-native/pull/XXXX))
+- Attach the on-error Session Replay buffer to feedback submitted from the feedback form ([#6870](https://github.com/getsentry/sentry-react-native/pull/6870))
 
 ### Dependencies