chore: set release version in changelog, add missing entry

Author: kantai

CHANGELOG.md

@@ -5,19 +5,23 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to the versioning scheme outlined in the [README.md](README.md).
 
-## [Unreleased]
+## [3.1.0.0.3]
 
 ### Added
 
 - Add `tenure_timeout_secs` to the miner for determining when a time-based tenure extend should be attempted.
 - Added configuration option `block_proposal_max_age_secs` under `[connection_options]` to prevent processing stale block proposals
 
 ### Changed
-- The RPC endpoint `/v3/block_proposal` no longer will evaluate block proposals more than `block_proposal_max_age_secs` old
 
+- The RPC endpoint `/v3/block_proposal` no longer will evaluate block proposals more than `block_proposal_max_age_secs` old
 - When a transaction is dropped due to replace-by-fee, the `/drop_mempool_tx` event observer payload now includes `new_txid`, which is the transaction that replaced this dropped transaction. When a transaction is dropped for other reasons, `new_txid` is `null`. [#5381](https://github.com/stacks-network/stacks-core/pull/5381)
 - Nodes will assume that all PoX anchor blocks exist by default, and stall initial block download indefinitely to await their arrival (#5502)
 
+### Fixed
+
+- Signers no longer accept messages for blocks from different reward cycles (#5662)
+
 ## [3.1.0.0.2]
 
 ### Added