Tapestry 5.4.3 is a drop-in replacement for Tapestry 5.4 releases. To upgrade, just update the dependency in your build configuration (Maven POM, Gradle build script, etc.) – or Download the new JAR file -- and the new version will just work. However, please review the How to Upgrade instructions before upgrading.
Release Notes - Tapestry 5 - Version 5.4.3