add a ?? to string reader for php8.1 in /src/Utils/StringReader.php

[lachlan-00]

https://github.com/php-gettext/Gettext/blob/3f7bc5ef23302a9059e64934f3d59e454516bec0/src/Utils/StringReader.php#L31

could we get this substr call edited to stop the depreciation errors for php8.1?

public function read($bytes)
    {
        $data = substr($this->str, $this->pos ?? 0, $bytes);

        $this->seekto($this->pos + $bytes);

        return $data;
    }

Or maybe just set it on construct?

    public function __construct($str)
    {
        $this->str = $str;
        $this->strlen = strlen($this->str);
        $this->pos = 0;
    }

The errors for translations on php8.1 are insanely loud when translating on php8.1

[Error] substr(): Passing null to parameter #2 ($offset) of type int is deprecated in file /var/www/music/vendor/gettext/gettext/src/Utils/StringReader.php(31)

I will be looking at moving to gettext5 but i don't really understand the code enough yet to do this for ampache

[oscarotero]

Can you create a PR with this fix? Thanks!

[lachlan-00]

merged with #287