Bump version to v0.3.4.

Author: jmalloc

CHANGELOG.md

@@ -10,7 +10,7 @@ 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
+## [0.3.4] - 2022-12-23
 
 ### Fixed
 
@@ -60,6 +60,7 @@ The format is based on [Keep a Changelog], and this project adheres to
 [0.3.0]: https://github.com/jmalloc/echo-server/releases/v0.3.0
 [0.3.1]: https://github.com/jmalloc/echo-server/releases/v0.3.1
 [0.3.2]: https://github.com/jmalloc/echo-server/releases/v0.3.2
+[0.3.4]: https://github.com/jmalloc/echo-server/releases/v0.3.4
 
 <!-- outside contributors -->