docs(core): Add timezone changelog entry

Author: adinauer

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+### Internal
+
+- Reduce Android startup overhead by using the default timezone directly on older devices or when no timezone info is available in the locale. ([#5587](https://github.com/getsentry/sentry-java/pull/5587))
+
 ## 8.43.1
 
 ### Fixes