playbooks/build-single-release.yaml should perform strict metadata verification

[webknjaz]

This playbook builds the dists but doesn't perform the metadata validation. That must happen early in the process. Specifically, calling twine check --strict must succeed. My pypi-upload action is invoked late in the process and it does perform a non-strict check, which may fail the upload last moment which would be unpleasant. The PyPI backend might also reject uploads because of the problems with dists, some of which (but not all) can be caught in the strict mode.
Running the check as early as possible (on merges to main and pull requests) reveals metadata problems in a way that they can be fixed before attempting to build though this workflow.

Putting it into the playbook would be useful. Something that could abort a release with broken meta.

Originally posted by @webknjaz in ansible-community/ansible-build-data#265 (comment)