Add skip duplicate action to workflow

This might be nice, I haven't tried it yet; an action that can be added to the workflow:

>Skip duplicate workflow-runs

>If you work with feature branches, then you might see lots of duplicate workflow-runs. For example, duplicate workflow-runs can happen if a workflow runs on a feature branch, but then the workflow is repeated right after merging the feature branch. skip-duplicate-actions allows to prevent such runs.

https://github.com/marketplace/actions/skip-duplicate-actions#skip-duplicate-workflow-runs