fix syntax

modules/fontane/transform.xqm

@@ -359,7 +359,7 @@ attribute class {
     let $anchor := $n/root()//tei:anchor[@xml:id = $thisMod/substring-after(@spanTo, '#')]
     return
       if($thisMod << $anchor)
-      then 'mod-seq-' || $thisMod/@seq)
+      then 'mod-seq-' || $thisMod/@seq
       else ()
   else (),
   if ($n/@type="illustration") then 'figure' else(),