👷(docker) add arm64 support and upgrade CI workflow steps (#11)

* 👷(docker) add arm64 platform support for image builds

Add QEMU and Buildx setup steps to enable multi-architecture Docker
image builds for both linux/amd64 and linux/arm64 platforms.

Signed-off-by: Stephan Meijer <me@stephanmeijer.com>

* ⬆️(ci) upgrade GitHub Actions workflow steps to latest versions

Update actions/setup-node from v4 to v6 and actions/cache from v4 to v5
for improved performance, security patches, and Node.js runtime compatibility.

Signed-off-by: Stephan Meijer <me@stephanmeijer.com>

---------

Signed-off-by: Stephan Meijer <me@stephanmeijer.com>

CHANGELOG.md

@@ -0,0 +1,11 @@
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0),
+and this project adheres to
+[Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Added
+
+- 👷(docker) add arm64 platform support for image builds