Bug: Url Helper have a bug

[mmrtonmoybd]

In url helper have a method url_title(). It can makes a slug from string. It also support Unicode. But it not totally support Unicode.
I tried to do a string to slug but codeigniter gives output:
$cname = "মশিউর রহমান";
echo url_title($cname, '-', TRUE);
Output: মশউর-রহমন

Expect: মশিউর-রহমান

I do few changes in system/Helpers/url_helper.php

In before
///////////////////////////////

function url_title(string $str, string $separator = '-', bool $lowercase = false): string
	{
		$q_separator = preg_quote($separator, '#');

		$trans = [
			'&.+?;'                   => '',
			'[^\w\d _-]'              => '',
			'\s+'                     => $separator,
			'(' . $q_separator . ')+' => $separator,
		];

		$str = strip_tags($str);
		foreach ($trans as $key => $val)
		{
			$str = preg_replace('#' . $key . '#iu', $val, $str);
		}

		if ($lowercase === true)
		{
			$str = mb_strtolower($str);
		}

		return trim(trim($str, $separator));
	}
}

/////////////////////////////
I do few changes
In after

function url_title(string $str, string $separator = '-', bool $lowercase = false, string $patran = ''): string
	{
		$q_separator = preg_quote($separator, '#');

		if ($patran != '') {
		  $trans = [
			'&.+?;'                   => '',
			$patran              => '',
			'\s+'                     => $separator,
			'(' . $q_separator . ')+' => $separator,
		];
		} else {
		   $trans = [
			'&.+?;'                   => '',
			'[^\w\d _-]'              => '',
			'\s+'                     => $separator,
			'(' . $q_separator . ')+' => $separator,
		];
		}

		$str = strip_tags($str);
		foreach ($trans as $key => $val)
		{
			$str = preg_replace('#' . $key . '#iu', $val, $str);
		}

		if ($lowercase === true)
		{
			$str = mb_strtolower($str);
		}

		return trim(trim($str, $separator));
	}
} 

////////////////

$cname = "মশিউর রহমান";
url_title($cname, '-', TRUE, '[^a-z0-9\x{0980}-\x{09ff}]');
Output: মশিউর-রহমান
It works and output same as my expected.
I add a pattern option that anyone can replace there string as they want.
I hope the changes will be add next version. If I do any worng. Please comment on this issue.