chore: Update changelog for v12.3.1 (#27465)

## **Description**

Update changelog for v12.3.1

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## **Related issues**

N/A

## **Manual testing steps**

N/A

## **Screenshots/Recordings**

N/A

## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I’ve included tests if applicable
- [x] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ## [12.3.1]
+### Fixed
+- Fix duplicate network validation ([#27463](https://github.com/MetaMask/metamask-extension/pull/27463))
+- Fix notification metrics ([#26807](https://github.com/MetaMask/metamask-extension/pull/26807))
+- Fix transaction metrics ([#27457](https://github.com/MetaMask/metamask-extension/pull/27457))
 
 ## [12.3.0]
 ### Added