update changelog before v8.3.1 release

CHANGELOG.md

@@ -34,23 +34,13 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 # Changelog
 
-## [[Unreleased]]
-
-### Dependencies
-
-### API Breaking
-
-### State Machine Breaking
+## [v8.3.1](https://github.com/cosmos/ibc-go/releases/tag/v8.3.1) - 2024-05-22
 
 ### Improvements
 * (core/ante) [\#6302](https://github.com/cosmos/ibc-go/pull/6302) Performance: Skip app callbacks during RecvPacket execution in checkTx within the redundant relay ante handler.
 * (core/ante) [\#6280](https://github.com/cosmos/ibc-go/pull/6280) Performance: Skip redundant proof checking in RecvPacket execution in reCheckTx within the redundant relay ante handler.
 * (core/ante) [\#6306](https://github.com/cosmos/ibc-go/pull/6306) Performance: Skip misbehaviour checks in UpdateClient flow and skip signature checks in reCheckTx mode.
 
-### Features
-
-### Bug Fixes
-
 ## [v8.3.0](https://github.com/cosmos/ibc-go/releases/tag/v8.3.0) - 2024-05-16
 
 ### Dependencies