chore: run workflow against base branch instead of always main

Description

All the PRs targetting feat/abac fail with breaking change, even though the breaking change is against main not feat/abac

[ ] I have clicked on "allow edits by maintainers".
[ ] I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above]
[ ] The correct base branch is being used, if not main
[ ] I have added tests to validate that the change in functionality is working as expected