Release a new major

[lode]

I want to release a new major version to do some cleanup. No new functions because there is no new jsonapi specification and I want to keep the upgrade small. Main changes:

• require php 8.2, the minimum still supported php version (from January 2026)
• cleanup old-style API, deprecated since v2.0
• cleanup deprecations from before final v1.1 of the specification, deprecated since v2.3
• add better type hinting

Follow the work here: https://github.com/lode/jsonapi/compare/v3?w=1

To Do:

• [x] #81
• [x] #82
• [x] #83
• [ ] strict type
• [ ] type hints
• [ ] improve ResourceInterface covering both Document and Objects, mainly visible with handling ResourceDocument->$resource
• [ ] lint, test, coverage