`helm lint` and `helm test` in CI before releasing Chart

[bitjson]

We should run helm lint and helm test in continuous integration before releasing new chart versions, see:

• https://github.com/helm/kind-action
• https://github.com/helm/chart-testing-action
• https://github.com/helm/charts-repo-actions-demo

It would be great to test the chart with all default settings (syncing a testnet4 node), then ensure the API is responding and working as expected – maybe send a query to ensure the sync has reached some block height.