Updated source file by EUROSTAT

[danielhuppmann]

Looks like Eurostat silently updated the NUTS xlsx file, the hash is now different - and unit tests in other repositories are failing because of it...

https://github.com/IAMconsortium/legacy-definitions/actions/runs/11296344229/job/31421010160?pr=18

The feature with downloading the xlsx from Eurostat is nice, but risky if this happens from time to time without any announcement or quick solution for downstream users.

Maybe instead keeping a json or yaml of the relevant data in the repo is a more stable solution, like https://github.com/pycountry/pycountry/tree/main/src/pycountry/databases?

[danielhuppmann]

Thinking about this further, I think a good solution would be the following:

• include the NUTS classification info as a hard-coded yaml in this repository
  (and make a release to solve downstream problems)
• move the tool to parse the Eurostat file (and create that yaml file) to a utility function in this package
• add a weekly GitHub workflow that checks whether the hash of the Eurostat file changed, so that we get an alert when Eurostat updates the file - so that we can check whether the actual NUTS codes/names changed...