fix: use local path source_folder if not empty

[Vinai]

This allows using the action in https://github.com/mage-os/generate-mirror-repo-js where the test module is an external package installed with composer. In this case, no local path repo configuration is needed.

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/graycoreio/github-actions-magento2/blob/main/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Currently the action fails if the local repo path url points to a non-existing folder or to a folder without a composer.json file.

What is the new behavior?

The action completes since no local path repo is configured

Does this PR introduce a breaking change?

• Yes
• No

Other information

[damienwebdev]

@Vinai I think you also meant to change this file.

github-actions-magento2/.github/workflows/integration.yaml

Line 129 in 94d044c

- run: composer config repositories.local path ${{ inputs.source_folder }}

[Vinai]

@damienwebdev Indeed you are right. That change got lost, not used to editing in the browser ;)