🐛 Consistently use lxml for etree

qurator/modstool/tests/test_alto.py

@@ -1,4 +1,4 @@
-import xml.etree.ElementTree as ET
+from lxml import etree as ET
 
 
 from qurator.modstool.alto4pandas import alto_to_dict

qurator/modstool/tests/test_mets.py

@@ -1,4 +1,4 @@
-import xml.etree.ElementTree as ET
+from lxml import etree as ET
 
 
 from qurator.modstool.modstool import mets_to_dict

qurator/modstool/tests/test_modstool.py

@@ -1,6 +1,6 @@
 from tkinter import W
+from lxml import etree as ET
 import pytest
-import xml.etree.ElementTree as ET
 
 
 from qurator.modstool.modstool import mods_to_dict