Kubeflow execution mode v1 compile is broken

[grahamia]

Describe the bug
Turns out that on doing #383 we have broken the dag v1 running currently used for kubeflow (executionMode == v1).

The v1 dag runner mandates the file extension to be certain values, yaml being one and not json so therefore on trying to do a compile now with executionMode v1 it fails in pipeline create workflow.

To Reproduce
Against a provider setup with executionMode v1 create a new pipeline resource so that the compiler step runs. It will fail with

ValueError: The output path /tmp/resource.json should ends with one of the following formats: [.tar.gz, .tgz, .zip, .yaml, .yml]

Expected behavior
Should compile and upload pipeline to kubeflow