Fix go-ci workflow
Fix go-ci workflow

Fix the go-ci workflow because its Build, Test, Lint step fails in forks of this project. This is because the workflow checks out code into go/src/github.com/${{ github.repository }} while our go code imports from go/src/github.com/GoogleContainerTools/kpt-functions-sdk/... Hardcode this path in the workflow so it will still pass in forks.

GoogleContainerTools/kpt-functions-sdk,GoogleContainerTools/kpt-functions-sdk,GoogleContainerTools/kpt-functions-sdk,GoogleContainerTools/kpt-functions-sdk