test: verify template GitHub workflows are valid and working as intended

[marcossevilla]

Overview

Add test coverage to verify that the GitHub workflow templates provided by very_good_workflows are valid, syntactically correct, and functioning as intended across different project types.

Tasks

• Identify all workflow templates currently provided by this repo
• Define what "valid and working as intended" means for each template (lint, test, publish, etc.)
• Write tests or validation scripts for each workflow template
• Ensure tests run in CI on every change to workflow templates
• Document the testing strategy in the contributing guide