[10.x] Random function doesn't generate evenly distributed random chars (#45916)

* Bugfix: The random function does not generate evenly distributed random characters particularly for short strings (<12 chars)

* fixed styling

* fixed styling

* formatting

---------

Co-authored-by: Jan Kramer <[email protected]>
Co-authored-by: Taylor Otwell <[email protected]>

Author: janh-kramer

Str.php

@@ -735,7 +735,9 @@ public static function random($length = 16)
             while (($len = strlen($string)) < $length) {
                 $size = $length - $len;
 
-                $bytes = random_bytes($size);
+                $bytesSize = (int) ceil(($size) / 3) * 3;
+
+                $bytes = random_bytes($bytesSize);
 
                 $string .= substr(str_replace(['/', '+', '='], '', base64_encode($bytes)), 0, $size);
             }