refactor: update PHPStan baseline and fix Rector

[michalsn]

Description
This PR updates the PHPStan baseline and one Rector error that occurred in the last build. IDK if there is a better way to handle PHPStan, but this seemed the simplest approach.

• PHPStan errors: https://github.com/codeigniter4/CodeIgniter4/actions/runs/14101988822/job/39499990729
• Rector error: https://github.com/codeigniter4/CodeIgniter4/actions/runs/14101988834/job/39499990763

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[michalsn]

Thank you @paulbalandan