Update cloned branch against latest source strings

[rffontenelle]

Translation teams update source strings in their own time and some branches doesn't get update to newer Python version, which means the clone repository has great chances of being out of date in comparison with the latest state of Python docs.

Consider generating POT files for the latest Python docs release and updating the PO files from cloned translation repositories before getting stats.

[m-aciek]

Agreed, though I see it as a feature of potodo to be used here: https://git.afpy.org/AFPy/potodo/issues/4.