Update changelog for 0.12.5 (#2665)

CHANGELOG.md

@@ -8,6 +8,14 @@ we recommend most users use the latest `master` branch of Teku.
 - REST API endpoints will be updated to match emerging standards in a future release.
 - `--validators-key-files` and `--validators-key-password-files` have been replaced by `--validator-keys`. The old arguments still work but will be removed in a future release.
 
+## 0.12.5
+
+### Bug Fixes
+
+- Fix race condition when a block and its parents are received at around the same time which could cause the node to fall out of sync until it reverted to syncing mode to catch up
+- Fix issue where attestations from blocks could be processed prior to the block they target being available resulting in `ProtoNode: Delta to be subtracted is greater than node weight` errors
+- Return a non-zero exit code from `validator register` subcommand when the user does not confirm the transaction
+
 ## 0.12.4
 
 ### Additions and Improvements