litespeed: add SPDX-License-Identifier header

python.d/litespeed.chart.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 # Description: litespeed netdata python.d module
 # Author: Ilya Maschenko (l2isbad)
+# SPDX-License-Identifier: GPL-3.0+
 
 import glob
 import re