REL: initialize next release cycle

CHANGELOG.md

@@ -4,6 +4,22 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added (for new features, dependecies etc.)
+
+### Changed (for changes in existing functionality)
+
+### Deprecated (for soon-to-be removed features)
+
+### Removed (for now removed features)
+
+### Fixed (for any bug fixes)
+
+### Security (in case of vulnerabilities)
+
+### Documentation (for notable additions or changes of the documentation)
+
 ## [0.4.0] - 2021-10-28
 
 ### Added (for new features, dependecies etc.)