prepare for 0.4.0 release

Author: Phil Varner

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](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-## [Unreleased] - TBD
+## [v0.4.0] - 2022-06-08
 
 ### Added
 
@@ -201,7 +201,7 @@ are in a single HTTP session, handle pagination and respects conformance
 
 Initial release.
 
-[Unreleased]: <https://github.com/stac-utils/pystac-client/compare/v0.3.5...main>
+[v0.4.0]: <https://github.com/stac-utils/pystac-client/compare/v0.3.5...v0.4.0>
 [v0.3.5]: <https://github.com/stac-utils/pystac-client/compare/v0.3.4..v0.3.5>
 [v0.3.4]: <https://github.com/stac-utils/pystac-client/compare/v0.3.3..v0.3.4>
 [v0.3.3]: <https://github.com/stac-utils/pystac-client/compare/v0.3.2..v0.3.3>

pystac_client/version.py

@@ -1 +1 @@
-__version__ = "0.3.5"
+__version__ = "0.4.0"