First parameter of `assign` in SQLUpdate not escaped

[NoLdman]

In https://github.com/bummzack/sortablefile/blob/0028923180b10d7613ff239a0fd56acdf96872ab/src/Forms/SortableUploadField.php#L199 the first parameter of assign isn't escaped, which causes SilverStripe-Installations with PostgreSQL databases to cast the column to lower-case (i.e. "sortorder").

Shouldn't it be escaped as follows?

->assign("\"$sortColumn\"", $sort++)