Automate testing and publishing of the chart (GitHub Actions)

[mostafa]

• https://helm.sh/docs/topics/chart_repository/
• https://github.com/helm/chart-releaser
• https://helm.sh/docs/howto/chart_releaser_action/
• https://github.com/marketplace/actions/kind-cluster
• https://github.com/marketplace/actions/helm-chart-testing
• https://dev.to/kitarp29/running-kubernetes-on-github-actions-f2c

[mostafa]

Automated testing is done in #12. Publishing is still WIP.