simplify test setup with github-action-add-on-test, fixes #21

[rfay]

The Issue

• Update github workflow to use github-action-add-on-test #21

The github setup should be using github-action-add-on-test

How This PR Solves The Issue

Use it.

[rfay]

Please check this @julienloizelet, thanks.

[rfay]

This fails DDEV HEAD just because that's failing right now. Will be fixed in

• Failing with DDEV HEAD due to permissions on /run/php #20

[julienloizelet]

Hi @rfay ,

LGTM but we could also remove the DDEV_GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} at the top of the file:
the DDEV_GITHUB_TOKEN is in fact also handled by the add-ons-test action itself.

[rfay]

Removed, thanks!