Add action outputs

[deminearchiver]

This PR add an outputs field to the action.yml metadata file. This field is not required, but with it some code editors (like VSCode with the GitHub Actions extension, for example) gain the ability to provide autocomplete for ${{ steps.<id>.outputs.<output_name> }}.

For more information, please see Outputs for JavaScript actions.

[nprogers]

Thank you for your help in maintaining this repository 🧡. We've migrated to wrangler-action and are making improvements to ensure that contributions like this will be more easily integrated and better supported. Please come join us at wrangler-action!