chore: update psalm.xml

[kenjis]

Description
Update to fix errors with CI 4.5.0 like:

Error: src/Auth.php:54:15: MissingDependency: CodeIgniter\Shield\Models\UserModel depends on class or interface codeigniter\basemodel that does not exist (see https://psalm.dev/157)
Error: src/Auth.php:139:23: UndefinedFunction: Function CodeIgniter\Shield\config does not exist (see https://psalm.dev/021)
Error: src/Auth.php:162:36: MissingDependency: CodeIgniter\Shield\Models\UserModel depends on class or interface codeigniter\basemodel that does not exist (see https://psalm.dev/157)

CI 4.5.0 requires PHP 8.1 or later.

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