Fix the changelog titles (#1785)

CHANGELOG.md

@@ -4,7 +4,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased](https://github.com/ruflin/Elastica/compare/7.0.0-beta.4...master)
+## [Unreleased](https://github.com/ruflin/Elastica/compare/7.0.0...master)
 ### Backward Compatibility Breaks
 ### Added
 
@@ -16,7 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Security
 
 
-## [Unreleased](https://github.com/ruflin/Elastica/compare/7.0.0-beta.4...7.0.0)
+## [7.0.0](https://github.com/ruflin/Elastica/compare/7.0.0-beta.4...7.0.0)
 ### Added
 * Added `Elastica\Aggregation\WeightedAvg` aggregation [#1770](https://github.com/ruflin/Elastica/pull/1770)