WordPress - Remove inline CSS from .wp-caption (plugin)

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<?php
/*
Plugin Name: FixWpCaption
Plugin URI: #
Description: Removes inline CSS from .wp-caption
*/
class FixWpCaption{

    public function __construct(){
        add_filter('img_caption_shortcode', array($this, 'fixcaption'), 10, 3);
    }
    public function fixcaption($x=null, $attr, $content){

        extract(shortcode_atts(array(
                'id'    => '',
                'align'    => 'alignnone',
                'width'    => '',
                'caption' => ''
            ), $attr));

        if ( 1 > (int) $width || empty($caption) ) {
            return $content;
        }

    return '<aside class="wp-caption ' . $align . '">'
    . $content . '<p class="wp-caption-text">' . $caption . '</p></aside>';
    }
    
}
$FixWpCaption = new FixWpCaption();

?>