feat: Default stackableVersion to operator version (#381)

* Default stackableVersion to operator version

* update docs and tests

* charts

* changelog

* fix tests

* trigger ci

Author: sbernauer

CHANGELOG.md

@@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
 
+### Added
+
+- Default stackableVersion to operator version ([#381]).
+
+[#381]: https://github.com/stackabletech/hdfs-operator/pull/381
+
 ## [23.7.0] - 2023-07-14
 
 ### Added