ci: upgrade github actions versions

[this-is-tobi]

Description

Upgrade all GitHub Actions used across CI workflows to their latest major versions.

Action	Before	After
actions/checkout	@v4	@v6
actions/setup-node	@v4	@v6
actions/cache	@v4	@v5
actions/upload-artifact	@v4	@v7
actions/download-artifact	@v4	@v8
docker/setup-buildx-action	@v3	@v4
docker/setup-qemu-action	@v3	@v4
docker/login-action	@v3	@v4
docker/build-push-action	@v6	@v7
docker/metadata-action	@v5	@v6

Also removed the always-auth input from actions/setup-node in npm.yml, as it was dropped in v6. Authentication still works via registry-url + NODE_AUTH_TOKEN.

Type of change

• Other (please describe): CI/CD maintenance — GitHub Actions version upgrades

How Has This Been Tested?

Versions verified against each action's latest GitHub release. No logic change, only action version pins updated.

Test Configuration:

• Toolchain: GitHub Actions

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

[github-actions]

🤖 Hey !

The security scan report for the current pull request is available here.