Validate YAML syntax in license dump tests

[Shaurya-dev7]

Fixes #3947

Tasks

• Reviewed contribution guidelines
• PR is descriptively titled 📑 and links the original issue above 🔗
• Tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR
• Commits are in uniquely-named feature branch and has no merge conflicts 📁
• Updated documentation pages (if applicable)
• Updated CHANGELOG.rst (if applicable)

Summary

Add YAML syntax validation checks during the license dump workflow using PyYAML validation.

This also extends the related tests to ensure invalid YAML content raises an error instead of silently passing through the dump generation flow.

Changes

• Added a helper validation function for generated YAML content in license_db.py
• Added YAML syntax validation during license dump generation
• Added test coverage for invalid YAML handling using pytest monkeypatch
• Improved error reporting for YAML parsing failures