v5.0.3

This PR introduces new validation enforcements on tags.mitre_attack_id field. It is not longer possible to declare overlapping techniques and sub-techniques. For example, both T1000 and T1000.001 cannot be defined.
However, any combination of non-overlapping techniques and sub-techniques remains valid.

What's Changed

• Cleanup mitre actors and techniques by @pyth0n1c in #363

Full Changelog: v5.0.2...v5.0.3