Release a new major #84

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:

• Cleanup deprecations #81
• Cleanup old-style API #82
• Increase the minimum php version #83
• Add strict type hints #85
• Upgrade code for new features from php 8.2 and dependencies #86
• Increase test and linting coverage #87
• Last cleanup and documentation for new release #88
• Write release notes