docs: add Unreleased section to changelog

Author: daniel-jones-dev

CHANGELOG.md

@@ -5,6 +5,15 @@ 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]
+### Added
+### Changed
+### Deprecated
+### Removed
+### Fixed
+### Security
+
+
 ## [1.12.0] - 2023-01-09
 ### Added
 * State explicitly that this library supports Python 3.11.
@@ -216,6 +225,7 @@ Version increased to avoid conflicts with old packages on PyPI.
 Initial version.
 
 
+[Unreleased]: https://github.com/DeepLcom/deepl-python/compare/v1.12.0...HEAD
 [1.12.0]: https://github.com/DeepLcom/deepl-python/compare/v1.11.0...v1.12.0
 [1.11.0]: https://github.com/DeepLcom/deepl-python/compare/v1.10.0...v1.11.0
 [1.10.0]: https://github.com/DeepLcom/deepl-python/compare/v1.9.0...v1.10.0