Lubuntu: Fix GeoIP parsing
With the recent switch of the GeoIP service, the format has also changed from
JSON to XML. This was not correctly changed in the welcome module for Lubuntu.
- Start Calamares (e.g. with an IP address from Europe).
- Check, that the language is set correctly (e.g. French when in France).
Reviewers: wxl, tsimonq2, kc2bez
Reviewed By: wxl, kc2bez
Differential Revision: https://phab.lubuntu.me/D101