Bump version to v0.3.0.

CHANGELOG.md

@@ -9,7 +9,7 @@ The format is based on [Keep a Changelog], and this project adheres to
 [Keep a Changelog]: https://keepachangelog.com/en/1.0.0/
 [Semantic Versioning]: https://semver.org/spec/v2.0.0.html
 
-## [Unreleased]
+## [0.3.0] - 2021-08-16
 
 - Add the `/.see` route
 
@@ -25,6 +25,7 @@ The format is based on [Keep a Changelog], and this project adheres to
 [Unreleased]: https://github.com/jmalloc/echo-server
 [0.1.0]: https://github.com/jmalloc/echo-server/releases/v0.1.0
 [0.2.0]: https://github.com/jmalloc/echo-server/releases/v0.2.0
+[0.3.0]: https://github.com/jmalloc/echo-server/releases/v0.3.0
 
 <!-- outside contributors -->
 [@arulrajnet]: https://github.com/arulrajnet