Grafana k8s Monitoring

What's Changed

• Add action to build the test image by @petewall in https://github.com/grafana/k8s-monitoring-helm/pull/323
• [dependency] Update Grafana Agent by @github-actions in https://github.com/grafana/k8s-monitoring-helm/pull/324

Full Changelog: https://github.com/grafana/k8s-monitoring-helm/compare/v0.8.0...v0.8.1