refactor: TypeError in strict mode by ArrayHelper::SortValuesByNatural()

[kenjis]

Description
Follow-up #8285

1) CodeIgniter\Helpers\Array\ArrayHelperSortValuesByNaturalTest::testSortWithStringValues
TypeError: strnatcmp(): Argument #2 ($string2) must be of type string, int given

/home/runner/work/CodeIgniter4/CodeIgniter4/system/Helpers/Array/ArrayHelper.php:318
/home/runner/work/CodeIgniter4/CodeIgniter4/system/Helpers/Array/ArrayHelper.php:313
/home/runner/work/CodeIgniter4/CodeIgniter4/tests/system/Helpers/Array/ArrayHelperSortValuesByNaturalTest.php:60

2) CodeIgniter\Helpers\Array\ArrayHelperSortValuesByNaturalTest::testSortWithArrayValues
TypeError: strnatcmp(): Argument #2 ($string2) must be of type string, int given

/home/runner/work/CodeIgniter4/CodeIgniter4/system/Helpers/Array/ArrayHelper.php:315
/home/runner/work/CodeIgniter4/CodeIgniter4/system/Helpers/Array/ArrayHelper.php:313
/home/runner/work/CodeIgniter4/CodeIgniter4/tests/system/Helpers/Array/ArrayHelperSortValuesByNaturalTest.php:84

https://github.com/codeigniter4/CodeIgniter4/actions/runs/7135744955/job/19433071552?pr=8307

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

[kenjis]

@neznaika0 Review, please.

[kenjis]

GitHub Action checks fail in 4.5 branch.
This PR will fix it. Review first.

[kenjis]

@michalsn Thank you!

[neznaika0]

I wonder why the PR check doesn't show this? Type casting helps, but is it worth adding the is_int is_string exception? When the value is a multidimensional array or object

[kenjis]

Because the PR was created and checked before adding declare(strict_types=1).

If the method does not work on unexpected arrays, it is better to check the value types.