fix: typo in pager default_simple

[jasonliang-dev]

Description
getnext -> getNext

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]

Can you run:

vendor/bin/phpstan analyse --generate-baseline phpstan-baseline.php

to fix the PHPStan error?

[michalsn]

Thank you.

[samsonasik]

Thank you @jasonliang-dev