SVG fix for MODX 3 S3 source

mimeFix.plugin.php

<?php
switch ($modx->event->name) {
    case "OnFileManagerUpload":
        if(!empty($files)){
            foreach($files as $file){
                $path = $directory . $source->sanitizePath($file['name']);
                $object = $source->getObjectContents($path);
                if(empty($object) || empty($object['mime']) || empty($object['content'])) continue;
                switch($object['mime']) {
                    case 'image/svg':
                    case 'image/svg+xml':
                        if (substr($object['content'],0,5) !== "<?xml") {
                            $content = "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">\n".$object['content'];
                            $source->updateObject($path, $content);
                        }
                        break;
                }
            }
        }
        break;
}
return;