Bump jupyterhub/action-k3s-helm from 3 to 4

Bumps [jupyterhub/action-k3s-helm](https://github.com/jupyterhub/action-k3s-helm) from 3 to 4.
- [Release notes](https://github.com/jupyterhub/action-k3s-helm/releases)
- [Changelog](https://github.com/jupyterhub/action-k3s-helm/blob/main/CHANGELOG.md)
- [Commits](jupyterhub/action-k3s-helm@v3...v4)

---
updated-dependencies:
- dependency-name: jupyterhub/action-k3s-helm
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/test-helm-template.yaml

@@ -54,7 +54,7 @@ jobs:
       # kubectl and helm.
       #
       # ref: https://github.com/jupyterhub/action-k3s-helm/
-      - uses: jupyterhub/action-k3s-helm@v3
+      - uses: jupyterhub/action-k3s-helm@v4
         with:
           k3s-channel: ${{ matrix.k3s-channel }}
           metrics-enabled: false