tools/check-version-history: avoid DeprecationWarning with newer lxml

tools/check-version-history: avoid DeprecationWarning with newer lxml

We get the same warning thousands of times:
/work/src/tools/check-version-history.py:28: FutureWarning: This search incorrectly
ignores the root element, and will be fixed in a future version. If you rely on the
current behaviour, change it to
"./refsynopsisdiv/funcsynopsis/funcprototype/funcdef/function[.='udev_device_get_properties_list_entry']"

We also need to update the ignorelist to the new form.