Add pypi changelog

Author: rzats

src/client/packaging/pypi/CHANGELOG.md

@@ -0,0 +1,19 @@
+# Change Log
+All notable changes to this client will be documented in this file.
+ 
+The format is based on [Keep a Changelog](http://keepachangelog.com/)
+and this project adheres to [Semantic Versioning](http://semver.org/).
+ 
+## [4.2.0] - 2023-09-27
+  
+### Added
+
+### Changed
+ 
+- Modify the signatures for several methods: endpoint no longer needs to be specified in the params dict under the "source" key, but becomes a mandatory parameter for the method:
+  - `_request(params)` → `_request(endpoint, params={})`
+  - `_request_with_retry(params)` → `_request_with_retry(endpoint, params={})`
+  - `async_epidata(param_list, batch_size=50)` → `async_epidata(endpoint, param_list, batch_size=50)`
+
+### Fixed
+