style: use `@PHP84Migration` ruleset

[DjordyKoert]

Description

use @PHP84Migration ruleset

What type of PR is this? (check all applicable)

• [ ] Bug Fix
• [ ] Feature
• [ ] Refactor
• [ ] Deprecation
• [ ] Breaking Change
• [ ] Documentation Update
• [ ] CI

Checklist

• [ ] I have made corresponding changes to the documentation (docs/)
• [ ] I have made corresponding changes to the changelog (CHANGELOG.md)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.50%. Comparing base (9f6c6a3) to head (c5524ea). Report is 1 commits behind head on master.

:white_check_mark: All tests successful. No failed tests found.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2398 +/- ## ======================================= Coverage 89.50% 89.50% ======================================= Files 78 78 Lines 2896 2896 ======================================= Hits 2592 2592 Misses 304 304 ```

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