Removed broken links

CHANGELOG.md

@@ -7,16 +7,16 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 
-## [Unreleased]
+## Unreleased
 
-## [1.8.1] - 2021-03-21
+## 1.8.1 - 2021-03-21
 
 ### Fixed
 
 - Issue parsing IPv6 URLs
 - Issue modifying ServerRequest lost all its attributes
 
-## [1.8.0] - 2021-03-21
+## 1.8.0 - 2021-03-21
 
 ### Added
 
@@ -28,7 +28,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Issue when creating stream from `php://input` and curl-ext is not installed
 - Broken `Utils::tryFopen()` on PHP 8
 
-## [1.7.0] - 2020-09-30
+## 1.7.0 - 2020-09-30
 
 ### Added
 
@@ -272,7 +272,6 @@ Currently unsupported:
 
 
 
-[Unreleased]: https://github.com/guzzle/psr7/compare/1.6.0...HEAD
 [1.6.0]: https://github.com/guzzle/psr7/compare/1.5.2...1.6.0
 [1.5.2]: https://github.com/guzzle/psr7/compare/1.5.1...1.5.2
 [1.5.1]: https://github.com/guzzle/psr7/compare/1.5.0...1.5.1