update changelog

Author: bcwu

CHANGELOG.md

@@ -4,6 +4,12 @@ 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).
 
+## [Unreleased]
+
+### Changed
+
+Update pip_freeze to use `pip freeze` since Connect filters for valid package paths in the backend and it no longer depends on the undocumented behavior of `pip list --format=freeze`. This reverts the change made in 1.5.2.
+
 ## [1.12.1] - 2022-11-07
 
 ### Changed