9.6 release: create changelogs and releases (#19342)

Co-authored-by: Brad Jorsch <anomiex@users.noreply.github.com>

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/701869416

CHANGELOG.md

@@ -5,13 +5,9 @@ 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 [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [1.13.3-alpha] - unreleased
-
-This is an alpha version! The changes listed here are not final.
-
+## [1.13.3] - 2021-03-30
 ### Added
 - Composer alias for dev-master, to improve dependencies
-- Created a changelog from the git history with help from [auto-changelog](https://www.npmjs.com/package/auto-changelog). It could probably use cleanup!
 
 ### Changed
 - Update package dependencies.
@@ -137,7 +133,7 @@ This is an alpha version! The changes listed here are not final.
 
 - Create package for Jetpack Tracking
 
-[1.13.3-alpha]: https://github.com/Automattic/jetpack-tracking/compare/v1.13.2...v1.13.3-alpha
+[1.13.3]: https://github.com/Automattic/jetpack-tracking/compare/v1.13.2...v1.13.3
 [1.13.2]: https://github.com/Automattic/jetpack-tracking/compare/v1.13.1...v1.13.2
 [1.13.1]: https://github.com/Automattic/jetpack-tracking/compare/v1.13.0...v1.13.1
 [1.13.0]: https://github.com/Automattic/jetpack-tracking/compare/v1.12.0...v1.13.0