[Php80] Handle has silent void on StringableForToStringRector

[samsonasik]

    public function __toString()
    {
        if (rand(0, 1)) {
            return 'something';
        }
    }

should add return '' on last root return:

        if (rand(0, 1)) {
            return 'something';
        }
+      return '';

[samsonasik]

All checks have passed 🎉 @TomasVotruba I am merging ;)

[github-actions]

This pull request has been automatically locked because it has been closed for 150 days. Please open a new PR if you want to continue the work.