add changelog entry

Author: szokeasaurusrex

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 "You know what they say. Fool me once, strike one, but fool me twice... strike three." — Michael Scott
 
+## Unreleased
+
+### Deprecations
+
+- Added a deprecation notice for release bundle uploads, a legacy method for uploading sourcemaps ([#2844](https://github.com/getsentry/sentry-cli/pull/2844)). Release bundle uploads will be removed in Sentry CLI 3.x in favor of artifact bundles, the newer sourcemap upload method [introduced in Sentry version 23.6.2](https://github.com/getsentry/sentry/commit/f90f764fda09575f3f94caf32d04589098384616). **Self-hosted users**: You must upgrade to Sentry 23.6.2 or later before upgrading to Sentry CLI 3.x.
+
 ## 2.56.1
 
 ### Deprecations