Add a new utility to update the translation from upstream

[egeakman]

Will be added in 0.1.2 0.2.0

[egeakman]

Something like https://github.com/python/python-docs-tr/blob/3.12/merge.py

[m-aciek]

Cross-posting from Discord: I think a similar script would be of a great value as a package available on PyPI, especially if multiple repositories would use it. That way it would be easier to update the script to have bugfixes, optimizations or features in multiple repositories, instead of different script versions everywhere.

Also Weblate integration script does a similar logic in its CI. In Weblate POC the script is updating POTs from upstream, copying also commit messages from the upstream (https://github.com/m-aciek/python-docs-weblate/commits/main/.pot).