CHANGELOG update and LINT fixes

CHANGELOG.md

@@ -3,6 +3,12 @@
 All notable changes to this project will be documented in this file.
 Given the high speed of development in the first phase, changes are being reported only starting from v0.20.2.
 
+## [Unreleased]
+
+### Added
+
+- Simplified script API to interact with platform variables (https://git.platypush.tech/platypush/platypush/-/issues/206).
+
 ## [0.23.0] - 2022-03-01
 
 ### Added

platypush/context/__init__.py

@@ -3,7 +3,7 @@ import importlib
 import logging
 
 from threading import RLock
-from typing import Optional, Callable, Any
+from typing import Optional, Any
 
 from ..bus import Bus
 from ..config import Config