prepared 6.3.7

Author: mkalkbrenner

CHANGELOG.md

@@ -4,7 +4,13 @@ All notable changes to the Solarium library will be documented in this file.
 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]
+## [6.3.7]
+### Added
+- Additional test coverage
+
+### Changed
+- PHPUnit 9 → 10
+
 ### Removed
 - PHP 8.0 support