Need automated testing via `go test`

[applejag]

Based on https://github.com/iver-wharf/iver-wharf.github.io/issues/75

Need to run Go tests and goimports formatting tests on commits and pull requests automatically.

As Wharf cannot do this yet, we should aim at using GitHub Actions.

Either we use the starter-workflow for Go https://github.com/actions/starter-workflows/blob/1d8891efc2151b2290b1d93e8489f9b1f41bd047/ci/go.yml which simply runs go test

Or we could look into a better integrated solution that could report failing tests as annotations inside the pull requests, such as:

• https://github.com/marketplace/actions/golang-test
• https://github.com/marketplace/actions/golang-test-annotations