update codeowners for LM (#1038)

## Motivation
LM team needs to power to approve it's own

## Solution
Remove strict code ownership

CODEOWNERS

@@ -139,8 +139,9 @@ flake.lock @smartcontractkit/prodsec-public
 /core/ @smartcontractkit/ccip
 /contracts/ @smartcontractkit/ccip-onchain @makramkd @elatoskinas @RayXpub
 
-# leave snapshots as ownerless
+# leave snapshots & changeset as ownerless
 /contracts/gas-snapshots/
+/contracts/.changeset/
 
 # CCIP LM
 /core/services/ocr2/plugins/liquiditymanager/ @smartcontractkit/liquidity-manager