Preview does not deploy if the link-checker fails

[brian-rose]

As I found out over at ProjectPythia/physical-oceanography-cookbook#9, if there is a link-checker failure for a PR, the action that deploys the preview does not run.

This is a bug in the workflow. The preview should be independent of the link checker.

[brian-rose]

I'm about to attempt some refactoring of the workflows to move more of the boilerplate code into reusable workflows housed in https://github.com/ProjectPythiaCookbooks/cookbook-actions. I'll see if I can resolve this bug while I'm at it.