Str::reverse() does not support PHP 7.0

[kjohnson]

Details

The Str helper method reverse uses the function mb_str_split, which requires PHP 7 >= 7.4.0, PHP 8.

FILE: .../runner/work/givewp/givewp/src/Framework/Support/Facades/Str.php
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FOUND 1 ERROR AFFECTING 1 LINE
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 565 | ERROR | The function mb_str_split() is not present in PHP
     |       | version 7.3 or earlier
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class Str
{
    public static function reverse($value)
    {
        return implode(array_reverse(mb_str_split($value)));
    }
}

[kjohnson]

We could either require polyfill-mbstring as a dependency or remove the Str::reverse method, which isn't currently being used anywhere.