style: add missing trailing newline to site_head template

Author: kehach07

trac-env/templates/site_head.html

@@ -14,4 +14,4 @@
 </script>
 # if req.path_info.startswith('/ticket/'):
   <script type="text/javascript" src="${href.chrome('site/tickethacks.js')}"></script>
-# endif
+# endif